docs: add fileset upload gh action

Author: jeremydw

example/.github/workflows/fileset-upload.yml

@@ -0,0 +1,41 @@
+# Uploads to fileset. Requirements:
+#   1. Specify `env.SITE` and `env.GOOGLE_CLOUD_PROJECT`.
+#   2. Add a secret `GCP_SA_KEY`.
+name: 'Fileset upload'
+on: [create, push]
+jobs:
+  deploy:
+    runs-on: ubuntu-latest
+    env:
+      GOOGLE_CLOUD_PROJECT: ''
+      SITE: ''
+    steps:
+    - uses: actions/checkout@v2
+      with:
+        fetch-depth: 1
+    - name: Cache node modules
+      uses: actions/cache@v2
+      env:
+        cache-name: cache-node-modules
+      with:
+        path: |
+          ~/.npm
+          **/node_modules
+        key: ${{ runner.os }}-build-${{ env.cache-name }}-${{ hashFiles('**/package-lock.json') }}
+        restore-keys: |
+          ${{ runner.os }}-build-${{ env.cache-name }}-
+          ${{ runner.os }}-build-
+          ${{ runner.os }}-
+    - name: Set up `gcloud` SDK
+      uses: google-github-actions/setup-gcloud@master
+      with:
+        project_id: ${{ env.GOOGLE_CLOUD_PROJECT }}
+        service_account_key: ${{ secrets.GCP_SA_KEY }}
+        export_default_credentials: true
+    - name: Build
+      run: |-
+        npm install
+        npm run build
+    - name: Upload
+      run: |-
+        npx @blinkk/fileset upload -s ${{ env.SITE }} -b ${GITHUB_REF#refs/heads/} build