Add API docs for status updates.

Review Request #8548 — Created Nov. 20, 2016 and submitted — Latest diff uploaded


Review Board


This change adds the stub files and fixture data to generate API documentation
for the status updates resource. In doing this, I found that the examples for
this were showing 401 errors rather than the actual data, because of the new
required_features flag. I've added support for this to the API extension in a
couple ways. First, we temporarily enable the feature while doing the requests
to form the examples. Second, the required features are listed in the
documentation output.

Built HTML docs and verified the results.