Merge pull request #102 from google/readme

Add usage instructions to README, tweak install instructions

README.md

@@ -48,21 +48,31 @@ Note that Vroom requires a version of vim built with the `+clientserver`
 option (run `vim --version` to check).  See `:help clientserver` for
 additional requirements.
 
-The easiest way to install vroom is to cd into the vroom directory and run
+If you're on Ubuntu or Debian, you can install
+[release packages](https://github.com/google/vroom/releases) from GitHub.
+
+Otherwise, the easiest way to install vroom is to clone the vroom repository
+from GitHub, cd into the vroom directory, and run
 ```sh
 python3 setup.py build && sudo python3 setup.py install
 ```
 
-You can also install
-[release packages](https://github.com/google/vroom/releases) from github. To
-build deb packages yourself, make sure you have a recent stdeb version with
-python 3 support installed.
-
 Vim 7.4.384 and later have built-in syntax support for the vroom filetype. You
 can install the standalone
 [ft-vroom plugin](https://github.com/google/vim-ft-vroom) for older versions of
 vim.
 
+## Usage
+
+Vroom is invoked from the command-line on `.vroom` files.
+
+```sh
+vroom myplugin/vroom/somefile.vroom
+```
+
+See `vroom --help` and https://github.com/google/vroom/wiki for more info on
+usage.
+
 ## Vroom cheat sheet
 
 Below is a table of the special symbols and conventions vroom recognizes. See