Remove most references to wiki from the README

* Replace most references to the wiki with appropriate docs.opscode.com
  content.
* Put a link to learnchef at the very top for new users
* Half of the development guide was "how to install from source"; make
  that its own section instead of linking to wiki.
Update copyright footer in the readme
Merge branch 'nowiki'

Updates the README to point to docs.opscode.com when possible.