Add Pull Request template

Related to #786 (comment)

Author: nagyv

.github/pull_request_template.md

@@ -0,0 +1,11 @@
+## PR Checklist
+
+For a smooth review process, please run through this checklist before submitting a PR.
+
+- [ ] Resource attributes match 1:1 the names and structure of the API resource in the GitLab API documentation.
+- [ ] Docs are updated with any new resources or attributes, including how to import the resource.
+- [ ] New resources should have at minimum a basic test with three steps:
+    - Create the resource
+    - Update the attributes
+    - Import the resource
+- [ ] No new //lintignore comments that came from copied code. Linter rules are meant to be enforced on new code.