Add missing crate READMEs and other cleanup (#458)

* Adds READMEs for the `libcnb-data` and `libcnb-proc-macros` crates,
  since previously they were bundling the repo root README, which was
  confusing when looking at their crates.io listing (#274).
* Corrects the MSRV listed in the READMEs so it matches that defined in
  each crate's `Cargo.toml` after #445.
* Adds badges to READMEs that didn't have them, to improve discoverability
  of the docs (eg towards #402) and awareness of latest version of each crate.
  Note: `libcnb-cargo` does not have a docs link since it's a binary not a library.
* Syncs the `libcnb-cargo` usage example output with the latest output
  used in the repo root README.
* Switches the docs.rs URLs style from `/*/` to `/latest/` since the former
  resolves to an exact version, which if bookmarked (or search engine indexed)
  will get out of date.
* Various other small tweaks.

Fixes #274.
Addresses part of #402.

README.md

@@ -1,15 +1,17 @@
-# libcnb.rs [![Build Status]][ci] [![Docs]][docs.rs] [![Latest Version]][crates.io] [![Rustc Version 1.58+]][rustc]
+# libcnb.rs   [![Build Status]][ci] [![Docs]][docs.rs] [![Latest Version]][crates.io] [![MSRV]][install-rust]
 
 [Build Status]: https://img.shields.io/github/workflow/status/heroku/libcnb.rs/CI/main
 [ci]: https://github.com/heroku/libcnb.rs/actions/workflows/ci.yml?query=branch%3Amain
 [Docs]: https://img.shields.io/docsrs/libcnb
-[docs.rs]: https://docs.rs/libcnb/*/libcnb/
+[docs.rs]: https://docs.rs/libcnb/latest/libcnb/
 [Latest Version]: https://img.shields.io/crates/v/libcnb.svg
 [crates.io]: https://crates.io/crates/libcnb
-[Rustc Version 1.58+]: https://img.shields.io/badge/rustc-1.58+-lightgray.svg
-[rustc]: https://blog.rust-lang.org/2022/01/13/Rust-1.58.0.html
+[MSRV]: https://img.shields.io/badge/MSRV-rustc_1.59+-lightgray.svg
+[install-rust]: https://www.rust-lang.org/tools/install
 
-`libcnb.rs` is a framework for writing [Cloud Native Buildpacks](https://buildpacks.io) in Rust. It is an opinionated implementation adding language constructs and convenience methods for working with the spec. It values strong adherence to the spec and data formats.
+`libcnb.rs` is a framework for writing [Cloud Native Buildpacks](https://buildpacks.io) in Rust.
+It is an opinionated implementation adding language constructs and convenience methods for working
+with the spec. It values strong adherence to the spec and data formats.
 
 It currently targets version `0.6` of the CNB spec.
 
@@ -25,17 +27,18 @@ be carried out once and don't need to be repeated for each buildpack you will wr
 
 #### libcnb Cargo Command
 
-Start by installing the libcnb Cargo command which we will later use to package our buildpack:
+Start by installing [libcnb-cargo](https://crates.io/crates/libcnb-cargo), which provides the `libcnb` Cargo command
+that we will use later to package our buildpack:
 
 ```shell
 $ cargo install libcnb-cargo
 ```
 
 #### Cross-compilation prerequisites
 
-It is common to write and build your buildpack on a platform that is different from the platform the buildpack will
-eventually run on. This means we have to cross-compile our buildpack. The `libcnb package` Cargo command tries to help you setting
-up your environment depending on your host platform, but we always need the appropriate target platform for Rust which 
+It is common to write and build your buildpack on a platform that is different from the platform on which the buildpack will
+eventually run. This means we have to cross-compile our buildpack. The `libcnb package` Cargo command tries to help you set
+up your environment depending on your host platform, but we always need the appropriate target platform for Rust, which
 we can install with `rustup`:
 
 ```shell
@@ -89,8 +92,8 @@ id = "*"
 
 That's all we need! We can now move on to finally write some buildpack code!
 
-
 ### Writing the Buildpack
+
 As aforementioned, the buildpack we're writing will be very simple. We will just log a "Hello World" message during the build
 and set the default process type to a command that will also emit "Hello World" when the application image is run. 
 Find more complex example buildpacks in the [examples directory](examples).
@@ -199,12 +202,7 @@ application code at all, we just create an empty directory and use that as our a
 ```shell
 $ mkdir bogus-app
 $ pack build my-image --buildpack target/buildpack/debug/libcnb-examples_my-buildpack --path bogus-app --builder heroku/builder:22
-22: Pulling from heroku/builder
-Digest: sha256:0e1db52b480805c63b793a1c0155ea30cabffbf7977f722c88dc42cef750a1d1
-Status: Image is up to date for heroku/builder:22
-22-cnb: Pulling from heroku/heroku
-Digest: sha256:3fd7866f22dcbcd3a72c7ab4b47728dcfbaacfa9730341d0fb10665f63d93788
-Status: Image is up to date for heroku/heroku:22-cnb
+...
 ===> ANALYZING
 Previous image with name "my-image" not found
 ===> DETECTING
@@ -230,6 +228,7 @@ Successfully built image my-image
 ```
 
 ### Running the image
+
 The newly created Docker image can be run in the same way as you would a Docker image created via `docker build`.
 If all went well, you should see our "Hello World!" message in your terminal:
 
@@ -239,6 +238,7 @@ Hello World!
 ```
 
 ### Next Steps
+
 While the buildpack we've written in this quick start guide is not very useful, it can serve as a starting point for a 
 more useful buildpack. To discover more of the libcnb API, browse the [examples directory](examples) and the 
 [documentation on docs.rs][docs.rs].

libcnb-cargo/README.md

@@ -1,6 +1,6 @@
-# libcnb-cargo
+# libcnb-cargo   [![Latest Version]][crates.io] [![MSRV]][install-rust]
 
-Cargo command for managing buildpacks written with [libcnb.rs](https://github.com/heroku/libcnb.rs).
+A Cargo command for managing buildpacks written with [libcnb.rs](https://github.com/heroku/libcnb.rs).
 
 ## Installation
 
@@ -18,12 +18,17 @@ project directory:
 $ cargo libcnb package
 INFO - Reading buildpack metadata...
 INFO - Found buildpack libcnb-examples/my-buildpack with version 0.1.0.
-INFO - Building buildpack binary (x86_64-unknown-linux-musl)...
-Compiling my-buildpack v0.1.0 (/Users/manuel.fuchs/projects/my-buildpack)
+INFO - Determining automatic cross-compile settings...
+INFO - Building binaries (x86_64-unknown-linux-musl)...
 # Omitting compilation output...
-Finished dev [unoptimized + debuginfo] target(s) in 2.67s
+    Finished dev [unoptimized + debuginfo] target(s) in 4.29s
 INFO - Writing buildpack directory...
-INFO - Successfully wrote buildpack directory: target/debug/libcnb-examples_my-buildpack_0.1.0 (53.1M)
+INFO - Successfully wrote buildpack directory: target/buildpack/debug/libcnb-examples_my-buildpack (3.26 MiB)
 INFO - Packaging successfully finished!
-INFO - Hint: To test your buildpack locally with pack, run: pack build my-image --buildpack target/debug/libcnb-examples_my-buildpack_0.1.0 --path /path/to/application
+INFO - Hint: To test your buildpack locally with pack, run: pack build my-image --buildpack target/buildpack/debug/libcnb-examples_my-buildpack --path /path/to/application
 ```
+
+[Latest Version]: https://img.shields.io/crates/v/libcnb-cargo.svg
+[crates.io]: https://crates.io/crates/libcnb-cargo
+[MSRV]: https://img.shields.io/badge/MSRV-rustc_1.59+-lightgray.svg
+[install-rust]: https://www.rust-lang.org/tools/install

libcnb-data/Cargo.toml

@@ -8,8 +8,8 @@ description = "Types for data formats specified in the Cloud Native Buildpack sp
 keywords = ["buildpacks", "CNB"]
 repository = "https://github.com/heroku/libcnb.rs/tree/main/libcnb-data"
 documentation = "https://docs.rs/libcnb-data"
-readme = "../README.md"
-include = ["src/**/*", "../LICENSE", "../README.md"]
+readme = "README.md"
+include = ["src/**/*", "../LICENSE", "README.md"]
 
 [dependencies]
 fancy-regex = { version = "0.10.0", default-features = false }

libcnb-data/README.md

@@ -0,0 +1,14 @@
+# libcnb-data   [![Docs]][docs.rs] [![Latest Version]][crates.io] [![MSRV]][install-rust]
+
+Provides types for data formats specified in the Cloud Native Buildpack specification.
+
+If you wish to create buildpacks using the [libcnb.rs](https://github.com/heroku/libcnb.rs)
+framework, use the [libcnb](https://crates.io/crates/libcnb) crate rather than depending
+on this crate directly.
+
+[Docs]: https://img.shields.io/docsrs/libcnb-data
+[docs.rs]: https://docs.rs/libcnb-data/latest/libcnb_data/
+[Latest Version]: https://img.shields.io/crates/v/libcnb-data.svg
+[crates.io]: https://crates.io/crates/libcnb-data
+[MSRV]: https://img.shields.io/badge/MSRV-rustc_1.59+-lightgray.svg
+[install-rust]: https://www.rust-lang.org/tools/install

libcnb-package/README.md

@@ -1,6 +1,4 @@
-# libcnb-package
-
-[![Docs]][docs.rs] [![Latest Version]][crates.io] [![Rustc Version 1.58+]][rustc]
+# libcnb-package   [![Docs]][docs.rs] [![Latest Version]][crates.io] [![MSRV]][install-rust]
 
 A library for cross-compiling and packaging buildpacks written with [libcnb.rs](https://github.com/heroku/libcnb.rs).
 
@@ -9,8 +7,8 @@ In most cases you should use [libcnb-cargo](https://crates.io/crates/libcnb-carg
 directly.
 
 [Docs]: https://img.shields.io/docsrs/libcnb-package
-[docs.rs]: https://docs.rs/libcnb/*/libcnb-package/
+[docs.rs]: https://docs.rs/libcnb-package/latest/libcnb_package/
 [Latest Version]: https://img.shields.io/crates/v/libcnb-package.svg
 [crates.io]: https://crates.io/crates/libcnb-package
-[Rustc Version 1.58+]: https://img.shields.io/badge/rustc-1.58+-lightgray.svg
-[rustc]: https://blog.rust-lang.org/2022/01/13/Rust-1.58.0.html
+[MSRV]: https://img.shields.io/badge/MSRV-rustc_1.59+-lightgray.svg
+[install-rust]: https://www.rust-lang.org/tools/install

libcnb-proc-macros/Cargo.toml

@@ -7,8 +7,8 @@ license = "BSD-3-Clause"
 description = "Procedural macros used within libcnb.rs"
 repository = "https://github.com/heroku/libcnb.rs/tree/main/libcnb-proc-macros"
 documentation = "https://docs.rs/libcnb-proc-macros"
-readme = "../README.md"
-include = ["src/**/*", "../LICENSE", "../README.md"]
+readme = "README.md"
+include = ["src/**/*", "../LICENSE", "README.md"]
 
 [lib]
 proc-macro = true

libcnb-proc-macros/README.md

@@ -0,0 +1,13 @@
+# libcnb-proc-macros   [![Docs]][docs.rs] [![Latest Version]][crates.io] [![MSRV]][install-rust]
+
+Procedural macros used within the [libcnb.rs](https://github.com/heroku/libcnb.rs) framework.
+
+In most cases you should use the [libcnb](https://crates.io/crates/libcnb) crate rather than
+depending on this crate directly.
+
+[Docs]: https://img.shields.io/docsrs/libcnb-proc-macros
+[docs.rs]: https://docs.rs/libcnb-proc-macros/latest/libcnb_proc_macros/
+[Latest Version]: https://img.shields.io/crates/v/libcnb-proc-macros.svg
+[crates.io]: https://crates.io/crates/libcnb-proc-macros
+[MSRV]: https://img.shields.io/badge/MSRV-rustc_1.59+-lightgray.svg
+[install-rust]: https://www.rust-lang.org/tools/install

libcnb-test/README.md

@@ -1,4 +1,4 @@
-# libcnb-test
+# libcnb-test   [![Docs]][docs.rs] [![Latest Version]][crates.io] [![MSRV]][install-rust]
 
 An experimental integration testing framework for Cloud Native Buildpacks written in Rust with libcnb.rs.
 
@@ -55,3 +55,10 @@ fn call_test_fixture_service(addr: std::net::SocketAddr, payload: &str) -> Resul
 - Only local Docker daemons are fully supported. If using Circle CI you must use the
   [`machine` executor](https://circleci.com/docs/2.0/executor-types/#using-machine) rather
   than the [remote docker](https://circleci.com/docs/2.0/building-docker-images/) feature.
+
+[Docs]: https://img.shields.io/docsrs/libcnb-test
+[docs.rs]: https://docs.rs/libcnb-test/latest/libcnb_test/
+[Latest Version]: https://img.shields.io/crates/v/libcnb-test.svg
+[crates.io]: https://crates.io/crates/libcnb-test
+[MSRV]: https://img.shields.io/badge/MSRV-rustc_1.59+-lightgray.svg
+[install-rust]: https://www.rust-lang.org/tools/install