Update pull_request_assignment.yml (Azure#19032)

* Update pull_request_assignment.yml

* Update pull_request_assignment.yml

Author: czubair

.github/pull_request_assignment.yml

@@ -25,6 +25,13 @@
       - "specification/eventgrid/data-plane/**"
     reviewers:
       - lmazuel
+      
+- rule:
+    # storage data-plane PR
+    paths:
+      - "specification/storage/data-plane/**"
+    reviewers:
+      - tg-msft
 
 - rule:
     # synapse data-plane PR