A change made in the upcoming 2.5.7 release included the addition of a

new related link for the review request resource. The implementatino of

get_related_links() accepted a review_request positional argument,

instead of an obj keyword argument, which ended up breaking doc

building.
This change renames the argument to obj in order to fix this. No other

behavior has changed.

Built the docs successfully (along with another upcoming change).