Added install instructions to readme.

README.md

@@ -4,13 +4,36 @@ Only works for single files, and is slooooooow. And when I say slow, I mean real
 And the compression rate? Not so god, in fact, the result is larger than the original.
 But hey, it works! And it's using freaking PI!!!
 
-## Compress
+## Install
+
+First of all, you will need to install rust.
+
+On OS X you can install using homebrew.
+
+```shell
+$ brew install rust
+```
+
+Or you can use the lovely [rustup](https://www.rustup.rs/) tool.
+
+Then it's just a matter of cloning and building.
+
+```shell
+$ git clone http://code.aceofba.se/logaritmisk/piar.git
+$ cd piar
+$ cargo build --release
+$ ./target/release/piar --help
+```
+
+## Usage
+
+### Compress
 
 ```shell
 $ piar -c my_file.txt my_file.pi
 ```
 
-## Decompress
+### Decompress
 
 ```shell
 $ piar -d my_file.pi my_file.txt