Edited section on modes in description to reflect as_json instead of to_hash.
Added section regarding Rails compatibility, created new heading for Compatibility.
Broke out the JSON Processing Alternatives section, and edited.
A bit more editing
Read it over a bit more and edited a few more things, changed the formatting a bit.
Hope you don't mind and find this helpful.
more edits top rails section
take -> make, and more specifics for how to get Oj working with which version.