Fix typo and add links to mocha and chai docs

README.md

@@ -15,12 +15,20 @@ Getting Started with Development
 * Click "Load unpacked extension..."
 * Point to the repo's directory
 
+Tests
+=====
+Please write tests! Our testing framework is mocha and our assertion library is
+chai:
+
+  * http://visionmedia.github.io/mocha/
+  * http://chaijs.com/api/assert/
+
 Tips/Tricks
 ===========
 
 * For Dev purposes, the test server always uses code 111111
 * Loading the `test.html` page may read, write or clear localStorage. To avoid
-  having to chooes between running tests and preserving your existing messages,
+  having to choose between running tests and preserving your existing messages,
   keys, and other extension data, much of the test suite can be run by starting
   a local webserver in the repository root, e.g. `python -m SimpleHTTPServer`.
   You can then access the test page at `http://0.0.0.0:8000`.