feat: Introduce PR welcome bot (kedacore#1151)

.github/workflows/pr-bot-welcome.yml

@@ -0,0 +1,28 @@
+name: PR Welcome Bot
+
+on:
+  pull_request_target:
+    types: [opened]
+    branches:
+    - 'main'
+
+permissions:
+  issues: write
+  pull-requests: write
+
+jobs:
+  pr_bot:
+    name: PR Bot
+    runs-on: ubuntu-latest
+    steps:
+      - name: 'Comment on PR'
+        uses: actions/github-script@v6
+        with:
+          github-token: ${{ secrets.GITHUB_TOKEN }}
+          script: |
+            await github.rest.issues.createComment({
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              issue_number: ${{ github.event.number }},
+              body: 'Thank you for your contribution! 🙏 We will review your PR as soon as possible.\n\n\nWhile you are waiting, make sure to:\n\n\n- Add your contribution to all applicable KEDA versions\n- GitHub checks are passing\n- Is the DCO check failing? Here is [how you can fix DCO issues](https://github.com/kedacore/keda/blob/main/CONTRIBUTING.md#i-didnt-sign-my-commit-now-what)\n\n\nLearn more about:\n- How to become a [listed end-user](https://github.com/kedacore/keda-docs#become-a-listed-keda-user) or a [listed commerical offering](https://github.com/kedacore/keda-docs#become-a-listed-keda-commercial-offering)\n- Our [contribution guide](https://github.com/kedacore/keda-docs/blob/main/CONTRIBUTING.md)'
+            });