wt.exe default behavior #507

By default wt.exe opens new tab if no command is specified, according to documentation.

However, it does not seems to be the case, since the windowingBehavior property is set to useNew and new window is opened for every new instance.

I guess it may be helpful to add a line that says something like wt.exe behavior if affected by the windowingBehavior property.

At first I thought of creating this PR on my own, but then decided to write an issue, maybe the behavior is expected and I've missed something.