Add starter guidelines on article writing in CONTRIBUTING

Taken from a suggestion brought up in #138 where we have
a couple of points on what kind of format best works for
articles.
Merge pull request #142 from randomecho/copyedit-contributing

Add starter guidelines on article writing in CONTRIBUTING
Update checklist.html

As label got changed the actual description needed a change as well.
Merge pull request #143 from thomassjogren/patch-3

Update checklist.html
Altering read me text so that it's more clear that you need Jekyll to contribute to the codebase, but not contributing in general.
slight rewording
Merge pull request #147 from chippper/gh-pages

Reword the readme so that it's not so intimidating
application role article submission
Merge pull request #148 from a11yproject/roleApplicationArticle

application role article submission
Update _posts/2013-01-11-how-to-hide-content.md
Merge pull request #151 from 7mary4/patch-1

Update _posts/2013-01-11-how-to-hide-content.md
Code formatting update
Added last updated
Category fix
Small article reformatting + Added datestamp to resources
retina favicon
Merge pull request #153 from jamiethepiper/retina_favicon

retina favicon
XML-escape the title element

The content for the <title> element should be escaped in order to prevent an invalid XML document when in cases where the contains an ampersand (&) or less-than (<) characters.
Merge pull request #155 from barberboy/gh-pages

XML-escape the title element in atom.xml
Updated myths post