Correct creation command in "Create a Windows Service using BackgroundService"

[IEvangelist]

We need to update the windows service hosting document https://docs.microsoft.com/en-us/aspnet/core/host-and-deploy/windows-service?view=aspnetcore-5.0&tabs=visual-studio to mention that the service should be created passing the --contentRoot argument.

We might want to do the same here for good measure:

Related to : dotnet/AspNetCore.Docs#23387 (comment)

https://docs.microsoft.com/en-us/dotnet/core/extensions/windows-service#create-the-windows-service

[mrlife]

@IEvangelist Would you happen to know how the other version in the top comment (the sequence on this docs page) would look with a content root supplied? I can't find anything about adding that. Thanks for any help.