Add install guide note on Turnkey VM docs (#145)

Author: havardthom

json/nextcloud-vm.json

@@ -30,5 +30,10 @@
         "username": "admin",
         "password": null
     },
-    "notes": []
+    "notes": [
+        {
+            "text": "This VM requires extra installation steps, see install guide at `https://github.com/community-scripts/ProxmoxVE/discussions/144`",
+            "type": "warning"
+        }
+    ]
 }

json/owncloud-vm.json

@@ -30,5 +30,10 @@
         "username": "admin",
         "password": null
     },
-    "notes": []
+    "notes": [
+        {
+            "text": "This VM requires extra installation steps, see install guide at `https://github.com/community-scripts/ProxmoxVE/discussions/144`",
+            "type": "warning"
+        }
+    ]
 }