update client name in typescript.md (#24894)

Author: kazrael2119

specification/fist/resource-manager/readme.typescript.md

@@ -4,7 +4,7 @@ These settings apply only when `--typescript` is specified on the command line.
 Please also specify `--typescript-sdks-folder=<path to root folder of your azure-sdk-for-js clone>`.
 
 ``` yaml $(typescript)
-title: IotFirmwareDefenseClient
+title: IoTFirmwareDefenseClient
 typescript:
   azure-arm: true
   package-name: "@azure/arm-iotfirmwaredefense"