Tweak the PR template

Follow up to rubocop/rubocop@88c9214.

.github/PULL_REQUEST_TEMPLATE.md

@@ -5,15 +5,15 @@ The more detailed you are, the better.**
 
 Before submitting the PR make sure the following are checked:
 
+* [ ] The PR relates to *only* one subject with a clear title and description in grammatically correct, complete sentences.
 * [ ] Wrote [good commit messages][1].
 * [ ] Commit message starts with `[Fix #issue-number]` (if the related issue exists).
 * [ ] Feature branch is up-to-date with `master` (if not - rebase it).
 * [ ] Squashed related commits together.
 * [ ] Added tests.
+* [ ] Ran `bundle exec rake default`. It executes all tests and runs RuboCop on its own code.
 * [ ] Added an entry (file) to the [changelog folder](https://github.com/rubocop/rubocop-rails/blob/master/changelog/) named `{change_type}_{change_description}.md` if the new code introduces user-observable changes. See [changelog entry format](https://github.com/rubocop/rubocop/blob/master/CONTRIBUTING.md#changelog-entry-format) for details.
 * [ ] The PR relates to *only* one subject with a clear title
   and description in grammatically correct, complete sentences.
-* [ ] Run `bundle exec rake default`. It executes all tests and RuboCop for itself, and generates the documentation.
-* [ ] If this is a new cop, consider making a corresponding update to the [Rails Style Guide](https://github.com/rubocop-hq/rails-style-guide).
 
 [1]: https://chris.beams.io/posts/git-commit/