Add --locale parameter

Added UI locale parameter documentation

Author: artl93

docs/install/use-command-line-parameters-to-install-visual-studio.md

@@ -59,7 +59,7 @@ When you install Visual Studio 2017 RC from a command prompt, you can use the fo
 |  ```--sharedInstallDir <dir>``` | Optional: The target installation directory for shared payloads. |  
 | ```--compatInstallDir <dir>``` | Optional: The target installation directory for legacy compatibility payloads. |  
 |  ```--layoutDir <dir>```, ```--layoutDirectory <dir>``` | Optional: The layout directory in which to find packages.|
-
+|  ```--locale <language-locale>``` | Optional: Change the locale of the user interface for the installer. Setting will be preseved. |
 
 > [!IMPORTANT]
 > While Visual Studio 2017 RC in general is supported for use in a production environment, those workloads and components that are marked "Preview" in the installation UI are not supported for use in a production environment.