Auto merge of #3972 - rust-lang:oli-obk-patch-1, r=flip1995,Manishearth

Create PULL_REQUEST_TEMPLATE

changelog: none

addresses #3955 (comment)

.github/PULL_REQUEST_TEMPLATE

@@ -0,0 +1,28 @@
+<!--
+Thank you for making Clippy better!
+
+We're collecting our changelog from pull request descriptions.
+If your PR only updates to the latest nightly, you can leave the
+`changelog` entry as `none`. Otherwise, please write a short comment
+explaining your change.
+
+If your PR fixes an issue, you can add "fixes #issue_number" into this
+PR description. This way the issue will be automatically closed when
+your PR is merged.
+
+If you added a new lint, here's a checklist for things that will be
+checked during review or continuous integration.
+
+- [ ] Followed [lint naming conventions][lint_naming]
+- [ ] Added passing UI tests (including committed `.stderr` file)
+- [ ] `cargo test` passes locally
+- [ ] Executed `util/dev update_lints`
+- [ ] Added lint documentation
+- [ ] Run `cargo fmt`
+
+Note that you can skip the above if you are just opening a WIP PR in
+order to get feedback.
+
+Delete this line and everything above before opening your PR -->
+
+changelog: none

doc/adding_lints.md

@@ -394,6 +394,7 @@ Before submitting your PR make sure you followed all of the basic requirements:
 - [ ] `cargo test` passes locally
 - [ ] Executed `util/dev update_lints`
 - [ ] Added lint documentation
+- [ ] Run `cargo fmt`
 
 ### Cheatsheet