Narrow scope of support documentation

Summary:
  - Direct users to detailed bug report / feature reuqest documents.
  - Move "get more info" and "unreproducible problems" to bug reporting document.
  - Stop telling users to email us, and strongly encourage them to use primary channels.

Test Plan: Read documentation.

Reviewers: btrahan, chad

Reviewed By: btrahan, chad

Subscribers: epriestley

Differential Revision: https://secure.phabricator.com/D10808