Merge pull request #5827 from ehashman/archive-node-rkt

Archive unused #sig-node-rkt channel

communication/slack-config/channels.yaml

@@ -359,6 +359,7 @@ channels:
   - name: sig-node
   - name: sig-node-bug-scrub
   - name: sig-node-rkt
+    archived: true
   - name: sig-scalability
   - name: sig-scheduling
   # sig-security* channels are defined in sig-security/