[RFC] Allow PR authors to merge their own PR.

This change only applies to PRs authored by `libtock-rs` code owners.

To date, we have asked PR reviewers to merge PRs. In practice, this means the PR author writes something like "This PR is ready to merge" when it is ready to merge, and the PR reviewers respond with `bors r+`. I do not believe we have ever had a situation where a PR reviewer has given any other response. This seems like an unnecessary back-and-forth.

Author: Johnathan Van Why

doc/CodeReview.md

@@ -15,9 +15,8 @@ PR to `libtock-rs` can be divided into two categories:
 
 The owners of `libtock-rs` (listed [below](#owners)) determine whether a PR is
 an upkeep PR or a significant PR. PRs should be merged by the `libtock-rs`
-owners rather than the PR's author. PRs authored by `libtock-rs` owners should
-be merged by a reviewer rather than their author. In general, PRs should be
-merged using a `bors r+` command rather than the GitHub UI (see the [bors
+owners rather than the PR's author. In general, PRs should be merged using a
+`bors r+` command rather than the GitHub UI (see the [bors
 documentation](https://bors.tech/documentation/) for more information on bors).
 
 A PR may only be merged when all of the following are true: