Improve documentation style slightly.

Use more idiomatic style for comments, which includes a space after the
//. See
https://code.google.com/p/go-wiki/wiki/CodeReviewComments#Comment_Senten
ces.
Remove references to LockOSThread Wiki example; simply mention
runtime.LockOSThread() in README instead.
Other than docs, there are no code or behavior changes.
Modify README to note runtime.LockOSThread() is needed.

Fix missing runtime.LockOSThread() in example code.
Merge pull request #73 from go-gl/improve-documentation-style

Improve documentation style slightly.