add usage image.

Author: chrisdl

Sort.novaextension/README.md

@@ -2,11 +2,13 @@
 
 Extension for nova.app that allows you to perform simple sorting on highlighted text.
 
+![usage](https://raw.githubusercontent.com/chrisdl/nova-sort/master/usage.png)
+
 # Usage
 
 Currently you can sort in 4 different ways:
 
   - Sort multiple lines based on a regular 0-9a-z sort.
   - Sort one or more lines internally. For example a line saying `cba` will say `abc`.
   - Sort multiple lines based by length (the number of characters including whitespace).
-  - Sort multiple lines based on length but reversed.
+  - Sort multiple lines based on length but reversed.