ci: upload docs as archive (#18329)

Author: Borda

.github/workflows/docs-build.yml

@@ -184,6 +184,8 @@ jobs:
       fail-fast: false
       matrix:
         pkg-name: ["app", "fabric", "pytorch"]
+    env:
+      GCP_TARGET: "gs://lightning-docs-${{ matrix.pkg-name }}"
     steps:
       - uses: actions/download-artifact@v3
         with:
@@ -203,14 +205,22 @@ jobs:
       # Uploading docs to GCS, so they can be served on lightning.ai
       - name: Upload docs/${{ matrix.pkg-name }}/stable to GCS 🪣
         if: startsWith(github.ref, 'refs/heads/release/')
-        run: gsutil -m rsync -d -R docs/build/html/ gs://lightning-docs-${{ matrix.pkg-name }}/stable
+        run: gsutil -m rsync -d -R docs/build/html/ ${GCP_TARGET}/stable
 
       # Uploading docs to GCS, so they can be served on lightning.ai
       - name: Upload docs/${{ matrix.pkg-name }}/latest to GCS 🪣
         if: github.ref == 'refs/heads/master'
-        run: gsutil -m rsync -d -R docs/build/html/ gs://lightning-docs-${{ matrix.pkg-name }}/latest
+        run: gsutil -m rsync -d -R docs/build/html/ ${GCP_TARGET}/latest
 
       # Uploading docs to GCS, so they can be served on lightning.ai
       - name: Upload docs/${{ matrix.pkg-name }}/release to GCS 🪣
         if: startsWith(github.ref, 'refs/tags/')
-        run: gsutil -m rsync -d -R docs/build/html/ gs://lightning-docs-${{ matrix.pkg-name }}/${{  github.ref_name }}
+        run: gsutil -m rsync -d -R docs/build/html/ ${GCP_TARGET}/${{  github.ref_name }}
+
+      # Uploading docs as archive to GCS, so they can be as backup
+      - name: Upload docs as archive to GCS 🪣
+        if: startsWith(github.ref, 'refs/tags/')
+        working-directory: docs/build
+        run: |
+          zip ${{  github.ref_name }}.zip -r html/
+          gsutil cp ${{  github.ref_name }}.zip ${GCP_TARGET}