Some documentation in the README

CONTRIBUTING.md

@@ -1,7 +1,5 @@
 # Contributing
 
-*Note: This entire file is actually a lie. The project is not tested yet, but it will be, hopefully soon*
-
 If you'd like to contribute to the project, you can use the usual github pull-request flow:
 
 1. Fork the project

README.md

@@ -1,6 +1,28 @@
+*Note: very experimental (but usable) at this point, some more documentation
+soon to come.*
+
 ## Usage
 
-Not quite ready yet, sorry, check back in a few days.
+The plugin exposes the command `WritableSearch`, which takes an argument and
+some optional command-line flags, and performs a grep (or ack, or any other
+search command), with the given parameters. For example:
+
+``` vim
+:WritableSearch function_call\( -C5
+```
+
+The results are opened in a new window, and are very similar to what you would
+get from performing the search on the command-line. The difference is that you
+can now edit this buffer and, upon writing, the original files will be updated
+with the changes. This gives you a very simple and straightforward
+search-and-replace process.
+
+The command `:Rerun` defined in the search buffer can be used to perform the
+search again, with different flags. For example:
+``` vim
+:WritableSearch function_call\( -C5
+:Rerun -C1
+```
 
 ## Contributing