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_Sentences.
- Remove references to LockOSThread Wiki example; simply mention `runtime.LockOSThread()` in README instead.
- Other than docs, there are no code or behavior changes.

Closes #70.
Closes #69.