Add a workflow to build and deploy docs site (#8126)

.github/workflows/deploy_docs.yml

@@ -0,0 +1,20 @@
+name: Build and deploy Jekyll documentation site
+on:
+  pull_request:
+    branches:
+      - master
+jobs:
+  deploy_docs:
+    if: "!contains(github.event.commits[0].message, '[ci skip]')"
+    runs-on: 'ubuntu-latest'
+    steps:
+      - uses: actions/checkout@v2
+      - uses: actions/setup-ruby@v1
+        with:
+          ruby-version: 2.7.x
+      - name: Set up dependencies
+        run: bash .github/actions/bootstrap
+      - name: Build and Deploy
+        run: bash .github/actions/deploy_docs
+        env:
+          JEKYLL_PAT: ${{ secrets.GITHUB_TOKEN }}