update README

README.md

@@ -1,10 +1,23 @@
-`tomcat` – a [TOML](https://toml.io) parser in POSIX shell
+`tomcat` – a minimal [TOML](https://toml.io) parser for the command line.
 
 ## Installation
 
 ### From Source
 
-Clone this repository and move the `tomcat` binary wherever your operating
-system stores locally-installed binaries. This is usually `/usr/local/bin` or
-`$HOME/.local/bin` for your user. Make sure the installation location is in your
-`$PATH`.
+1. Run `cargo --install --git https://git.tebibyte.media/emma/tomcat.git`
+2. ???
+3. Profit
+
+## Usage
+
+To get the value of `key` from the `main` table in `file.toml`:
+
+`tomcat main.key file.toml`
+
+To get the top-level key `notable` from `file.toml`:
+
+`tomcat notable file.toml`
+
+To get index `3` in array `arr` inside the `main` table in `file.toml`:
+
+`tomcat main.arr[3] file.toml`