Add documentation for the new webhook resource.

Review Request #7524 — Created July 14, 2015 and submitted — Latest diff uploaded


Review Board


This change adds the pieces needed to generate docs for the new webhook
resource. Specifically, it adds new doc entries for webhook-list and webhook,
links in the index, and a fixture to auto-generate examples from.

While I was doing this, I encountered lots of trouble because the types for the
apply_to, encoding, and type fields weren't correct (they were lists of
specific strings rather than just being a generic six.text_type). This was
causing the docs to fail to build in a cryptic way as the webapi-resource
sphinx class tried to import "a.ll"

Build docs and looked at the results.