Add docs publication trigger for all branches (asciidoctor#782)

.github/workflows/deploy-docs.yml

@@ -0,0 +1,17 @@
+name: Deploy Docs
+on:
+  push:
+    branches:
+      - main
+      - v2.2.x
+    paths: [ 'docs/**' ]
+permissions: read-all
+jobs:
+  build:
+    if: github.repository_owner == 'asciidoctor'
+    runs-on: ubuntu-latest
+    steps:
+      - name: Trigger
+        env:
+          GH_TOKEN: ${{ secrets.GH_TOKEN_SCOPE_REPO }}
+        run: gh workflow run trigger.yml -R asciidoctor/docs.asciidoctor.org -r main