Clean README up a little

Not all section headers are h1 now, the list of SEE ALSO resources is
now easier to read.
Update pod for OAuth::Lite2::Endpoint::Token

I believe that this clarifies the intent of the methods. I have based
this on the original text and my only aim was to improve readability. I
am very open to discussing these changes and providing suggestions.
Merge pull request #2 from matthewfranglen/master

Update README and OAuth::Lite2::Endpoint::Token