[docs] - Updated help description for az vmss list-instances.

Author: william051200

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

@@ -2600,6 +2600,7 @@
 """
 
 helps['vmss list-instances'] = """
+type: command
 short-summary: List all virtual machines in a VM scale sets.
 parameters:
   - name: --resiliency-view