Apply label Doing if there is a related MR

.triage-policies.yml

@@ -127,6 +127,12 @@ resource_rules:
         actions:
           labels: 
             - "Status: Need triage"
+      - name: Apply in progress if merge request is opened
+        conditions:
+          ruby: issue.merge_requests_count > 0
+        actions:
+          labels:
+            - "Doing"
 
   merge_requests:
     rules: