Remove obsolete workflow files and add webhook event example

Author: goranrad

.github/workflows/custom-action.yml

@@ -0,0 +1,15 @@
+name: "Webhook Event example"
+
+on:
+  repository_dispatch:
+    types:
+      - webhook
+
+jobs:
+  respond-to-dispatch:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout repo
+        uses: actions/checkout@v2
+      - name: Run a script
+        run: echo "Event of type: $GITHUB_EVENT_NAME"