add deploy ci and update readme

.github/workflows/deploy.yml

@@ -0,0 +1,23 @@
+name: Deploy to production
+'on': [push]
+
+jobs:
+  lighthouse:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: zendesk/checkout@v3
+      - name: Setup Node.js
+        uses: zendesk/setup-node@v3
+        with:
+          node-version-file: '.nvmrc'
+      - name: Install node_modules
+        run: yarn install --frozen-lockfile
+      - name: Build
+        run: yarn build
+      - name: Upload theme
+        run: node ./bin/theme-upload.js
+        env:
+          ZENDESK_EMAIL: ${{ secrets.zendesk_email }}
+          ZENDESK_API_TOKEN: ${{ secrets.zendesk_token }}
+          ZENDESK_SUBDOMAIN: ${{ secrets.subdomain }}