Add /demo/ to commented deploy URL (#86)

Author: rebecca-shoptaw

.github/workflows/pr-preview.yml

@@ -14,6 +14,8 @@ on:
 
 concurrency: preview-${{ github.ref }}
 
+env:
+  PREVIEW_BRANCH: gh-pages
 jobs:
   deploy-preview:
     runs-on: ubuntu-latest
@@ -30,6 +32,29 @@ jobs:
       # Reference: https://github.com/rossjrw/pr-preview-action
       - name: Deploy preview
         uses: rossjrw/pr-preview-action@v1
+        id: preview-step
         with:
           source-dir: ./ghpages/
           umbrella-dir: pr
+          preview-branch: ${{ env.PREVIEW_BRANCH }}
+          comment: false
+        
+      - uses: marocchino/sticky-pull-request-comment@v2
+        if: steps.preview-step.outputs.deployment-action == 'deploy'
+        with:
+          header: pr-preview
+          message: |
+            [PR Preview Action](https://github.com/rossjrw/pr-preview-action) ${{ steps.preview-step.outputs.action-version }}
+            :---:
+            | <p></p> :rocket: View preview at <br> ${{ steps.preview-step.outputs.preview-url }}demo/ <br><br>
+            | <h6>Built to branch [`${{ env.PREVIEW_BRANCH }}`](${{ github.server_url }}/${{ github.repository }}/tree/${{ env.PREVIEW_BRANCH }}) at ${{ steps.preview-step.outputs.action-start-time }}. <br> Preview will be ready when the [GitHub Pages deployment](${{ github.server_url }}/${{ github.repository }}/deployments) is complete. <br><br> </h6>
+      
+      - uses: marocchino/sticky-pull-request-comment@v2
+        if: steps.preview-step.outputs.deployment-action == 'remove'
+        with:
+          header: pr-preview
+          message: |
+            [PR Preview Action](https://github.com/rossjrw/pr-preview-action) ${{ steps.preview-step.outputs.action-version }}
+            :---:
+            Preview removed because the pull request was closed.
+            ${{ steps.preview-step.outputs.action-start-time }}