Add comments_count to example json responses in calendar_events

calendar_events json response now returns the comment count. Updates
the example json responses accordingly.
Merge branch 'update-docs-with-comments_count-on-calendar_events'
Add `app_url` to json responses in documentation
Merge branch 'add-app_url-to-json-responses-docs'
Add API docs explaining how to get list of projects user has access to