fix test

dev-tools/omdb/tests/usage_errors.out

@@ -194,12 +194,17 @@ termination: Exited(2)
 stdout:
 ---------------------------------------------
 stderr:
-error: 'omdb mgs' requires a subcommand but one was not provided
-  [subcommands: inventory, help]
+Debug a specific Management Gateway Service instance
 
 Usage: omdb mgs [OPTIONS] <COMMAND>
 
-For more information, try '--help'.
+Commands:
+  inventory  Show information about devices and components visible to MGS
+  help       Print this message or the help of the given subcommand(s)
+
+Options:
+      --mgs-url <MGS_URL>  URL of an MGS instance to query [env: OMDB_MGS_URL=]
+  -h, --help               Print help
 =============================================
 EXECUTING COMMAND: omdb ["nexus"]
 termination: Exited(2)