docs: Tweak PR template to notify users they should mark them as draft when it makes sense (#3041)

Author: Eideren

.github/pull_request_template.md

@@ -28,3 +28,6 @@
 - [ ] I have added tests to cover my changes.
 - [ ] All new and existing tests passed.
 - [ ] **I have built and run the editor to try this change out.**
+
+<!--- Open this PR as a draft if it isn't ready yet, you can do so by clicking on the arrow next to the 'Create pull request' button. -->
+<!--- You will be able to set it back as ready to be reviewed anytime after it has been created. -->