Update README.md

`bundle` before `rake build` preventing `cannot load such file -- middleman-gh-pages` error
Merge pull request #12 from lgs/patch-1

Update README.md
fix copypasta
Merge pull request #17 from indirect/patch-1

fix copypasta
Update JSON Patch specs to the latest RFC 6902.

http://tools.ietf.org/html/rfc6902
Merge pull request #27 from seletskiy/json-patch-rfc-6902

Update JSON Patch specs to the latest RFC 6902
Deletions should not mandate a particular Accept header
Merge pull request #30 from celkins/excessive-delete-constraint

Deletions should not mandate a particular Accept header
Adding `extending` page and information.
Merge pull request #31 from json-api/extending

Adding `extending` page and information.
Notes section is really a Status section

* Rename the "Notes" section as "Status".
* Remove the emphasis from the entire section and
  place emphasis on the "work in progress" sentence.
* Call out that the spec is not stable.
* Rework paragraph about contributing.
* Tweak some grammar and punctuation (take the commas 
  from over here and push them over there -- Patrick).
Little typo fix
s/ID/URL

Btw, `a URL` or `an URL`?
Merge pull request #49 from RKushnir/patch-1

s/ID/URL
Merge pull request #48 from eoinoc/master

Little typo fix
Merge pull request #37 from reinh/patch-1

Notes section is really a Status section
Add note about content type.
No need to see 'extending' under see also on the extending page
Merge pull request #53 from gevious/master

Removed the extending link under 'see also' on the extending page
Fix media type for JSON patch.

We left off the +json

Fixes #42.