separating html from js (for syntax-highlighting)
Style guide fixes for the index, contributing, and About jQuery articles. Fixes #270
Add missing code fences in between sections of "Using jQuery's index() function" article to fix syntax highlighting. Fixes #278.
Style fixes on the About page. Fixes #279.

* Oxford commas.
* Period after second bullet point sentence.
* Em dashes instead of double-hyphens.
* Fix typo: "who need the right away" -> "who need them right away".
Code and prose style improvements to all articles in Ajax chapter. Fixes #283.
Remove double ampersands in README header. Fixes #284.
Style and typography fixes, and code style adherence in the Code Organization section. Fixes #287.
Style and typography fixes, and code style adherence in the Effects section. Fixes #290.
Style and typography fixes and code style adherence in the Events section. Fixes #294.
Update list of reserved words in JavaScript. Fixes #301.

All of these are only considered reserved when in strict mode, but it is in any case a more correct list than the current one. See https://github.com/jquery/learn.jquery.com/pull/295 for further discussion on how to present this list.