{Storage} fix help (Azure#16327)

Author: Jianhui Harold

src/azure-cli/azure/cli/command_modules/storage/_help.py

@@ -1991,7 +1991,7 @@
 short-summary: Manage the metadata for file in file system.
 """
 
-helps['storage fs metadata show'] = """
+helps['storage fs file metadata show'] = """
 type: command
 short-summary: Return all user-defined metadata for the specified file.
 examples: