[CI] Added preview bot

Author: mnocon

.github/workflows/preview_comment.yaml

@@ -0,0 +1,15 @@
+name: "Post preview links for changed files"
+
+on:
+    pull_request: ~
+
+jobs:
+    post-preview-links:
+        name: Post preview links for changed files
+        runs-on: ubuntu-latest
+        permissions:
+            # Needed to manage the comment
+            pull-requests: write
+        uses: ibexa/documentation-developer/.github/workflows/preview_comment.yamll@main
+        with:
+            project: 'projects/userguide/'