createMergeProposal under-documented and unfriendly API

[James Westby]

createMergeProposal takes a reviewers argument and a review_types argument,
but neither explain what they do. (prerequisite_branch and target_branch are also
under-documented, but they are more ovbious).

In addition, you have to pass a list to review_types if you pass one to reviewers,
but I think it would be nice if you didn't have to and if it got None it just assumed
[""] * len(reviewers).

Thanks,

James

[James Westby (james-w)]

Oh, and

  API-oriented version of addLandingTarget.

  The parameters are the same as addLandingTarget, except that
  review_requests is split into a list of reviewers and a list of review types.

isn't very useful external documentation as addLandingTarget is not
exposed.

Thanks,

James