added readme info

README.md

@@ -1,3 +1,21 @@
 # s
 
-A minimal shell.
+A minimal shell. It doesn’t do much, except, you know, executing commands.
+
+## Installation
+
+```
+git clone https://github.com/hellerve/s
+cd s
+make install
+```
+
+## Usage
+
+The shell can be entered through typing `s`. It has ephemeral editline
+capabilities, and the only builtins are `cd` and `exit`. There’s not
+much more to it.
+
+<hr/>
+
+Have fun!