Editorial: Update README.md

Improve prose for resources (i.e., `testharness.js`).

I have been educating the community on the benefits of aligning testing
with WPT. However, testharness is a little difficult to get head wrapped around
from the feedback I am receiving. Also have recently been doing some prose
updates in documentation over @ WHATWG. I am revisiting the WPT setup process
and believe one should always leave code better than when they saw it.

References:
  - whatwg/meta#48
  - (in particular) whatwg/meta#48 (comment)

resources/readme.md

@@ -1,22 +1,26 @@
-## Introduction ##
+# Resources
 
-testharness.js provides a framework for writing low-level tests of
+## `testharness.js`
+
+`testharness.js` is a framework for writing low-level tests of
 browser functionality in javascript. It provides a convenient API for
 making assertions and is intended to work for both simple synchronous
-tests and for tests of asynchronous behaviour.
+tests, and tests of asynchronous behaviour.
 
-## Getting Started ##
+### Getting started
 
 To use testharness.js you must include two scripts, in the order given:
 
 ``` html
-<script src="/resources/testharness.js"></script>
-<script src="/resources/testharnessreport.js"></script>
+<script src=/resources/testharness.js></script>
+<script src=/resources/testharnessreport.js></script>
 ```
 
-## Full documentation ##
+### Full documentation
+
+For detailed API documentation please visit [http://web-platform-tests.org/writing-tests/testharness-api.html](http://web-platform-tests.org/writing-tests/testharness-api.html).
 
-Full user documentation for the API is at [http://web-platform-tests.org/writing-tests/testharness-api.html](http://web-platform-tests.org/writing-tests/testharness-api.html).
+### Tutorials
 
 You can also read a tutorial on 
 [Using testharness.js](http://darobin.github.com/test-harness-tutorial/docs/using-testharness.html).