Merge pull request github#15310 from FlashSheridan/patch-2

Document optional install [user] argument

Author: ramyaparimi

content/actions/hosting-your-own-runners/configuring-the-self-hosted-runner-application-as-a-service.md

@@ -78,6 +78,12 @@ You can manage the runner service in the Windows **Services** application, or yo
    ```
 {% endmac %}
 
+The command takes an optional `user` argument to install the service as a different user.
+
+```shell
+./svc.sh install --user <em>USERNAME</em>
+```
+
 ## Starting the service
 
 Start the service with the following command: