Get a contributing.md into every of our repos

[jzaefferer]

Reference https://github.com/jquery/jquery/blob/master/CONTRIBUTING.md

[ajpiano]

I'd also like to add a central clearinghouse with links to all these pages - perhaps a jquery.org/contributing. I think we'll be able to adapt a lot of the content from the summit Wiki into some of these pages!

[jaspermdegroot]

This is the one we use for Mobile https://github.com/jquery/jquery-mobile/blob/master/CONTRIBUTING.md

[ajpiano]

Learn Site is good to go here!

[kswedberg]

Removing Core Docs label. Creating new issue at jquery/api.jquery.com

[RedWolves]

Added issues for both api.jqueryui.com and api.jquerymobile.com

[koop]

Took care of web-base-template, QUnit, plugins, themeroller, and mobile. That should cover it.