Updated pull request template

.github/PULL_REQUEST_TEMPLATE.md

@@ -3,7 +3,8 @@
 1. If this is your first time, please read our [`CONTRIBUTING.md`](https://github.com/grafana/grafana/blob/master/CONTRIBUTING.md) guide.
 2. Ensure you have added or ran the appropriate tests for your PR.
 3. If it's a new feature or config option it will need a docs update. Docs are under the docs folder in repo root.
-6. If the PR is unfinished, mark it as a draft PR.
+4. If the PR is unfinished, mark it as a draft PR.
+5. Rebase your PR if it gets out of sync with master
 -->
 
 **What this PR does / why we need it**: