reviewboard.reviews.actions defined an all_review_request_url_names,

which builds upon the URL names lists in reviewboard.urls to include

all reviewable content and the review request page.
This is useful, and worth including along with those lists, especially

as we prepare to document these.
This change adds that to reviewboard/urls.py, adds documentation for

the other lists, and indexes this in the code reference.

Unit tests pass.
Verified I could link to these lists in the docs pages.