Update resource list

Author: Autogenerator Pipeline

generator/resources.json

@@ -1577,7 +1577,8 @@
     "2020-11-01",
     "2020-12-01",
     "2021-02-01",
-    "2021-03-01"
+    "2021-03-01",
+    "2021-05-01"
   ],
   "Microsoft.ContainerService/managedClusters/agentPools": [
     "2019-02-01",
@@ -1596,12 +1597,14 @@
     "2020-11-01",
     "2020-12-01",
     "2021-02-01",
-    "2021-03-01"
+    "2021-03-01",
+    "2021-05-01"
   ],
   "Microsoft.ContainerService/managedClusters/maintenanceConfigurations": [
     "2020-12-01",
     "2021-02-01",
-    "2021-03-01"
+    "2021-03-01",
+    "2021-05-01"
   ],
   "Microsoft.ContainerService/managedClusters/privateEndpointConnections": [
     "2020-06-01",
@@ -1610,7 +1613,8 @@
     "2020-11-01",
     "2020-12-01",
     "2021-02-01",
-    "2021-03-01"
+    "2021-03-01",
+    "2021-05-01"
   ],
   "Microsoft.ContainerService/openShiftManagedClusters": [
     "2018-09-30-preview",