Please explain how to use the gst-build uninstalled environment

Submitted by nh2..@..tus.de

Description

I got very confused by https://github.com/GStreamer/gst-build/tree/c938c7591612b511cabfcf0b1788b10021186bf1#uninstalled-environment

Nothing in those docs indicated that I should call the script with the name of my shell as the first argument, e.g. ./gst-uninstalled.py bash or ./gst-uninstalled.py zsh, to get into the development environment.

Even though that program uses python's argparse CLI parser, it doesn't indicate in the help text, or in the linked README, that this should be done.

I only got the idea of how to use it by reading the code here: https://github.com/GStreamer/gst-build/blob/c938c7591612b511cabfcf0b1788b10021186bf1/gst-uninstalled.py#L230

Please add it to the docs and to the argparse --help output, thanks!