Unify docs workflows

.github/workflows/build_docs.yml

@@ -3,6 +3,11 @@
 name: Build PR Docs
 
 on:
+  push:
+    branches:
+      - main
+    tags:
+      - 'v*'
   pull_request:
     branches:
       - main
@@ -70,3 +75,36 @@ jobs:
         with:
           name: docs
           path: docs/docs/_build
+
+  deploy:
+    if: github.event_name == 'push' && (startsWith(github.ref, 'refs/tags/v') || startsWith(github.ref, 'refs/heads/main'))
+    name: Build & Upload Artifact
+    runs-on: ubuntu-latest
+    steps:
+      - name: Download artifact
+        uses: actions/download-artifact@v2
+        with:
+          name: docs
+          path: docs
+
+      - name: remove doctrees
+        run: rm -rf docs/.doctrees
+
+      - name: get directory name
+        # if this is a tag, use the tag name as the directory name else dev
+        run: |
+          if [[ "${{ github.ref }}" == "refs/tags/"* ]]; then
+            echo "branch_name=${{ github.ref/refs\/tags\// }}" >> $GITHUB_ENV 
+          else
+            echo "branch_name=dev" >> $GITHUB_ENV 
+          fi
+
+      - name: Deploy Docs
+        uses: peaceiris/actions-gh-pages@v3
+        with:
+          deploy_key: ${{ secrets.ACTIONS_DEPLOY_KEY }}
+          external_repository: napari/napari.github.io
+          publish_dir: docs/docs/_build
+          publish_branch: gh-pages
+          destination_dir: ${{ env.branch_name }}
+          cname: napari.org