add build workflow

.github/workflows/build.yml

@@ -0,0 +1,26 @@
+name: Run Build
+
+# Run action on pull request event
+on: [pull_request]
+
+
+jobs:
+  build:
+    runs-on: ubuntu-18.04
+    steps:
+    # checkout to the commit that has been pushed
+    - uses: actions/checkout@v2.4.0
+      with:
+        submodules: true  # Fetch Hugo themes (true OR recursive)
+        fetch-depth: 0    # Fetch all history for .GitInfo and .Lastmod
+
+    # install Hugo
+    - name: Setup Hugo
+      uses: peaceiris/actions-hugo@v2.5.0
+      with:
+        hugo-version: 'latest'
+        extended: true
+
+    # build website
+    - name: Build
+      run: hugo --minify