feat: add PR description skill

pr-description/SKILL.md

@@ -0,0 +1,22 @@
+---
+name: pr-description
+description: Pull request description format. Use when writing or editing a PR description.
+---
+
+# PR description
+
+Use this format. Keep every section concise and salient.
+
+```md
+### Problem
+
+<the problem or bug>
+
+### Solution
+
+<the solution>
+
+#### Details
+
+<bullet list of details>
+```

pr-description/agents/openai.yaml

@@ -0,0 +1,5 @@
+interface:
+  display_name: "PR Description"
+  short_description: "Write PR descriptions in the standard format"
+policy:
+  allow_implicit_invocation: true