Making go-local-coauthors-plus a bit more ready for public consumption

- Added a README.md file
- Tweaked some conditionals so `coauthors_posts_links` doesn't fall over in a non GO environment.
- Going forward autoload is set to 'no' on the cache option.
So in the name of getting this out.  I'm going to undo those changes and remove the function from the docs.  How's that?