[WIP] Write the README

README.md

@@ -4,6 +4,12 @@
 
 [![NuGet](https://img.shields.io/nuget/v/Chisel.svg?label=NuGet&logo=NuGet)](https://www.nuget.org/packages/Chisel/) [![Continuous Integration](https://img.shields.io/github/actions/workflow/status/0xced/Chisel/continuous-integration.yml?branch=main&label=Continuous%20Integration&logo=GitHub)](https://github.com/0xced/Chisel/actions/workflows/continuous-integration.yml)
 
+Chisel was born because some database drivers can't resist taking dependencies on cloud libraries. The [MongoDB driver](https://www.nuget.org/packages/MongoDB.Driver) depends on the ASW SDK for authentication with Identity and Access Management (IAM) and [Microsoft's SQL Server driver](https://www.nuget.org/packages/Microsoft.Data.SqlClient) depends on the Azure SDK for authentication with the Microsoft identity platform (formerly Azure AD).
+
+Users have asked for separate NuGet packages for both MongoDB ([issue #4635](https://jira.mongodb.org/browse/CSHARP-4635)) and SqlClient ([issue #1108](https://github.com/dotnet/SqlClient/issues/1108)) but as of `MongoDB.Driver` 2.24.0 and `Microsoft.Data.SqlClient` 5.2.0 the cloud dependencies are unavoidable, even if MongoDB or SQL Server is used on premises (where cloud authentication is obviously not needed).
+
+Enter Chisel to remove those dependencies and save some precious megabytes.
+
 ## Getting started
 
 Add the [Chisel](https://www.nuget.org/packages/Chisel/) NuGet package to your project using the NuGet Package Manager or run the following command:
@@ -12,3 +18,75 @@ Add the [Chisel](https://www.nuget.org/packages/Chisel/) NuGet package to your p
 dotnet add package Chisel
 ```
 
+While Chisel's main purpose is removing unwanted dependencies from existing NuGet packages, it provides another great feature: a graph of your project's dependencies. After adding Chisel, a [Mermaid](https://mermaid.js.org) (or [Graphviz](https://graphviz.org)) graph is written in the intermediate output path (aka the `obj` directory).
+
+For a project referencing the `Hangfire.PostgreSql` and `Npgsql.EntityFrameworkCore.PostgreSQL` packages the graph would look like this.
+
+```mermaid
+graph LR
+
+classDef default fill:aquamarine,stroke:#009061
+classDef project fill:skyblue,stroke:#05587C
+classDef ignored fill:lightgray,stroke:#7A7A7A
+classDef removed fill:lightcoral,stroke:#A42A2A
+
+Hangfire.Core --> Newtonsoft.Json
+Hangfire.PostgreSql --> Dapper
+Hangfire.PostgreSql --> Hangfire.Core
+Hangfire.PostgreSql --> Npgsql
+Microsoft.EntityFrameworkCore --> Microsoft.EntityFrameworkCore.Abstractions
+Microsoft.EntityFrameworkCore --> Microsoft.Extensions.Caching.Memory
+Microsoft.EntityFrameworkCore --> Microsoft.Extensions.Logging
+Microsoft.EntityFrameworkCore.Relational --> Microsoft.EntityFrameworkCore
+Microsoft.EntityFrameworkCore.Relational --> Microsoft.Extensions.Configuration.Abstractions
+Microsoft.Extensions.Caching.Abstractions --> Microsoft.Extensions.Primitives
+Microsoft.Extensions.Caching.Memory --> Microsoft.Extensions.Caching.Abstractions
+Microsoft.Extensions.Caching.Memory --> Microsoft.Extensions.DependencyInjection.Abstractions
+Microsoft.Extensions.Caching.Memory --> Microsoft.Extensions.Logging.Abstractions
+Microsoft.Extensions.Caching.Memory --> Microsoft.Extensions.Options
+Microsoft.Extensions.Caching.Memory --> Microsoft.Extensions.Primitives
+Microsoft.Extensions.Configuration.Abstractions --> Microsoft.Extensions.Primitives
+Microsoft.Extensions.DependencyInjection --> Microsoft.Extensions.DependencyInjection.Abstractions
+Microsoft.Extensions.Logging --> Microsoft.Extensions.DependencyInjection
+Microsoft.Extensions.Logging --> Microsoft.Extensions.Logging.Abstractions
+Microsoft.Extensions.Logging --> Microsoft.Extensions.Options
+Microsoft.Extensions.Logging.Abstractions --> Microsoft.Extensions.DependencyInjection.Abstractions
+Microsoft.Extensions.Options --> Microsoft.Extensions.DependencyInjection.Abstractions
+Microsoft.Extensions.Options --> Microsoft.Extensions.Primitives
+Npgsql --> Microsoft.Extensions.Logging.Abstractions
+Npgsql.EntityFrameworkCore.PostgreSQL --> Microsoft.EntityFrameworkCore
+Npgsql.EntityFrameworkCore.PostgreSQL --> Microsoft.EntityFrameworkCore.Abstractions
+Npgsql.EntityFrameworkCore.PostgreSQL --> Microsoft.EntityFrameworkCore.Relational
+Npgsql.EntityFrameworkCore.PostgreSQL --> Npgsql
+
+class Dapper default
+class Hangfire.Core default
+class Hangfire.PostgreSql default
+class Microsoft.EntityFrameworkCore default
+class Microsoft.EntityFrameworkCore.Abstractions default
+class Microsoft.EntityFrameworkCore.Relational default
+class Microsoft.Extensions.Caching.Abstractions default
+class Microsoft.Extensions.Caching.Memory default
+class Microsoft.Extensions.Configuration.Abstractions default
+class Microsoft.Extensions.DependencyInjection default
+class Microsoft.Extensions.DependencyInjection.Abstractions default
+class Microsoft.Extensions.Logging default
+class Microsoft.Extensions.Logging.Abstractions default
+class Microsoft.Extensions.Options default
+class Microsoft.Extensions.Primitives default
+class Newtonsoft.Json default
+class Npgsql default
+class Npgsql.EntityFrameworkCore.PostgreSQL default
+```
+
+## Removing the AWS SDK from MongoDB.Driver
+
+## Removing the Azure SDK from Microsoft.Data.SqlClient
+
+## Advanced configuration
+
+* `ChiselEnabled`
+* `ChiselGraphName` (`.mmd` or `.mermaid`)
+* `ChiselGraphDirection` (`LeftToRight` vs `TopToBottom`)
+* `ChiselGraphIncludeVersions`
+* `ChiselIgnores`