ci: add closed issue message (#804)

Author: Dane Pilcher

.github/workflows/closed-issue-message.yml

@@ -0,0 +1,15 @@
+name: Closed Issue Message
+on:
+  issues:
+    types: [closed]
+jobs:
+  auto_comment:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: aws-actions/closed-issue-message@v1
+        with:
+          # These inputs are both required
+          repo-token: '${{ secrets.GITHUB_TOKEN }}'
+          message: |
+            This issue is now closed. Comments on closed issues are hard for our team to see. 
+            If you need more assistance, please open a new issue that references this one.