feat: action to check microsite build

.github/workflows/microsite-build-check.yml

@@ -0,0 +1,52 @@
+name: Build microsite
+
+on:
+  pull_request:
+    paths:
+      - '.github/workflows/microsite-build-check.yml'
+      - 'microsite/**'
+      - 'docs/**'
+
+jobs:
+  build-microsite:
+    runs-on: ubuntu-latest
+
+    strategy:
+      matrix:
+        node-version: [12.x]
+
+    env:
+      CI: true
+      NODE_OPTIONS: --max-old-space-size=4096
+
+    steps:
+      - uses: actions/checkout@v2
+      - name: find location of global yarn cache
+        id: yarn-cache
+        run: echo "::set-output name=dir::$(yarn cache dir)"
+
+      - name: cache global yarn cache
+        uses: actions/cache@v2
+        with:
+          path: ${{ steps.yarn-cache.outputs.dir }}
+          key: ${{ runner.os }}-yarn-${{ hashFiles('**/yarn.lock') }}
+          restore-keys: |
+            ${{ runner.os }}-yarn-
+
+      - name: cache node_modules
+        uses: actions/cache@v2
+        with:
+          path: node_modules
+          key: ${{ runner.os }}-modules-${{ hashFiles('yarn.lock') }}
+
+      - name: use node.js ${{ matrix.node-version }}
+        uses: actions/setup-node@v1
+        with:
+          node-version: ${{ matrix.node-version }}
+          registry-url: https://registry.npmjs.org/ # Needed for auth
+
+      - name: yarn install
+        run: yarn install --frozen-lockfile
+
+      - name: build microsite
+        run: yarn workspace backstage-microsite build

.github/workflows/microsite-with-storybook-deploy.yml

@@ -11,7 +11,7 @@ on:
       - 'microsite/**'
 
 jobs:
-  deploy-storybook:
+  deploy-microsite-and-storybook:
     runs-on: ubuntu-latest
 
     strategy: