github: Add PR Template

Author: jmooring

.github/pull_request_template.md

@@ -0,0 +1,10 @@
+🛑 Before submitting this PR
+
+All PRs must be linked to an Issue in this repository, and that Issue must be approved by a project maintainer:
+
+- For a bug, approval means that the "needs triage" label is removed.
+- For a proposal, approval means that the "proposal" label is replaced by an "enhancement" label.
+
+PRs without a linked, approved Issue will be closed immediately.
+
+Please review the contribution guide (CONTRIBUTING.md) to understand commit message guidelines and AI assistance disclosures.