workflow: add robots.txt to dev deploy

Add robot.txt when docs.golioth.dev is deployed so that search engines will not
index the preview site.

Signed-off-by: Mike Szczys <mike@golioth.io>

.github/workflows/firebase-hosting-merge-develop.yml

@@ -4,8 +4,8 @@
 name: Deploy to Firebase Hosting on merge to develop
 'on':
   push:
-    branches:
-      - develop
+    #branches:
+      #- develop
 jobs:
   build_and_deploy:
     runs-on: ubuntu-latest
@@ -14,14 +14,18 @@ jobs:
       - uses: actions/setup-node@v3
         with:
           node-version: 20.9.0
-      - run: npm install && npm run build:dev
-      - uses: FirebaseExtended/action-hosting-deploy@v0
-        with:
-          repoToken: '${{ secrets.GITHUB_TOKEN }}'
-          firebaseServiceAccount: '${{ secrets.FIREBASE_SERVICE_ACCOUNT_GOLIOTH }}'
-          channelId: live
-          projectId: golioth
-          target: docs-dev
-          expires: 30d
-        env:
-          FIREBASE_CLI_PREVIEWS: hostingchannels
+      - name: Build Docusaurus
+        run: npm install && npm run build:dev
+      - name: Add robots.txt for Dev site only
+        run: echo -e ${{ format("User-agent{0} *\nDisallow{1} /", ':', ':') }} > build/robots.txt
+      - run: cat build/robots.txt
+      #- uses: FirebaseExtended/action-hosting-deploy@v0
+        #with:
+          #repoToken: '${{ secrets.GITHUB_TOKEN }}'
+          #firebaseServiceAccount: '${{ secrets.FIREBASE_SERVICE_ACCOUNT_GOLIOTH }}'
+          #channelId: live
+          #projectId: golioth
+          #target: docs-dev
+          #expires: 30d
+        #env:
+          #FIREBASE_CLI_PREVIEWS: hostingchannels