[MINOR] Protect asf-site branch to avoid accidental deletion

And update labels with tech stack
diff --git a/.asf.yaml b/.asf.yaml
index 7152ec3..9e5f9b4 100644
--- a/.asf.yaml
+++ b/.asf.yaml
@@ -27,6 +27,8 @@
   homepage: https://systemds.apache.org/
   labels:
     - systemds
+    - jekyll
+    - gulp
     
   features:
     # Enable issues management
@@ -55,6 +57,10 @@
       # This ensures that accident
       # Force `push`es won't happen.
       required_linear_history: true
+    asf-site:
+      # This ensures that accident
+      # Force `push`es won't happen.
+      required_linear_history: true
   
 # Web hosting
 staging: