Add install and use sections in Readme

Readme.md

@@ -4,6 +4,22 @@ A very simple configurable key overlay written in Rust.
 
 ![Screenshot of OwOverlay](screenshot.png)
 
+## How do I install?
+
+If you have the Rust toolchain installed, you can use `cargo`:
+
+```sh
+cargo install owoverlay
+```
+
+Eventually, binaries will be released in this repository.
+
+## How do I use it?
+
+See [cowonfig.toml](/cowonfig.toml) for an example config.
+
+Config documentation is coming soon!
+
 ## License
 
 This project is licensed under the MIT license.