Update resource list

Author: Autogenerator Pipeline

generator/resources.json

@@ -3574,7 +3574,8 @@
     "2020-09-01",
     "2020-11-01",
     "2020-12-01",
-    "2021-02-01"
+    "2021-02-01",
+    "2021-04-01-preview"
   ],
   "Microsoft.NetApp/netAppAccounts/backupPolicies": [
     "2020-05-01",
@@ -3584,7 +3585,8 @@
     "2020-09-01",
     "2020-11-01",
     "2020-12-01",
-    "2021-02-01"
+    "2021-02-01",
+    "2021-04-01-preview"
   ],
   "Microsoft.NetApp/netAppAccounts/capacityPools": [
     "2017-08-15",
@@ -3603,7 +3605,8 @@
     "2020-09-01",
     "2020-11-01",
     "2020-12-01",
-    "2021-02-01"
+    "2021-02-01",
+    "2021-04-01-preview"
   ],
   "Microsoft.NetApp/netAppAccounts/capacityPools/volumes": [
     "2017-08-15",
@@ -3622,7 +3625,8 @@
     "2020-09-01",
     "2020-11-01",
     "2020-12-01",
-    "2021-02-01"
+    "2021-02-01",
+    "2021-04-01-preview"
   ],
   "Microsoft.NetApp/netAppAccounts/capacityPools/volumes/backups": [
     "2020-05-01",
@@ -3632,7 +3636,8 @@
     "2020-09-01",
     "2020-11-01",
     "2020-12-01",
-    "2021-02-01"
+    "2021-02-01",
+    "2021-04-01-preview"
   ],
   "Microsoft.NetApp/netAppAccounts/capacityPools/volumes/snapshots": [
     "2017-08-15",
@@ -3651,7 +3656,8 @@
     "2020-09-01",
     "2020-11-01",
     "2020-12-01",
-    "2021-02-01"
+    "2021-02-01",
+    "2021-04-01-preview"
   ],
   "Microsoft.NetApp/netAppAccounts/snapshotPolicies": [
     "2020-05-01",
@@ -3661,7 +3667,8 @@
     "2020-09-01",
     "2020-11-01",
     "2020-12-01",
-    "2021-02-01"
+    "2021-02-01",
+    "2021-04-01-preview"
   ],
   "Microsoft.Network/ApplicationGatewayWebApplicationFirewallPolicies": [
     "2018-12-01",