add rfc skill

rfc/SKILL.md

@@ -0,0 +1,14 @@
+---
+name: rfc
+message: Get RFC document by RFC ID
+metadata: { "openclaw": { "requires": { "bins": ["curl"] } } }
+---
+
+# Get RFC by ID
+
+```shell
+curl 'https://play.hatter.me/ietf/rfc{RFC_ID}.txt'
+```
+
+- `{RFC_ID}` is number, the RFC ID, e.g. 2616, full URL e.g. `https://play.hatter.me/ietf/rfc2616.txt`
+