Expand troubleshooting for issues on Windows with python in git bash

The part https://carpentries-incubator.github.io/python-intermediate-development/common-issues.html#python-hangs-in-git-bash can be extended with the following related problem:

Does the file remain empty when using `winpty python -m pip freeze > requirements.txt`? Adjust the alias to `alias python='winpty -Xallow-non-tty python'`
- If that in turn adds strange characters, extend it further to `alias python='winpty -Xallow-non-tty -Xplain python'`
- [Solution source](https://superuser.com/a/1322277/519432)