Windows git bash TTY info

[thompsonmj]

In the section Warning: Git Bash on using git bash with Windows, add information about TTY so users can better understand error messages for commands such as:

$ docker container run -it alpine sh
the input device is not a TTY.  If you are using mintty, try prefixing the command with 'winpty'

Potentially repeat this point in the first relevant example under Exploring and Running Containers.

[sstevens2]

Thanks for reporting @thompsonmj! This is the first I've heard of this warning message in GitBash and I don't think I know enough about TTY to add info on it. I agree it seems like something we should mention to learners in call out. I'd recommend putting it under the first relevant example if that is the first time it comes up for learners using GitBash.

Would you want to right up a PR adding a callout with more about this message and what to do when you encounter it?