Add documentation for how to use maws under Windows

[gene1wood]

Should users be using the Windows Subsystem for Linux? cmd.exe? Git Bash mingw64?

I can confirm, talking to a user today, that the windows subsystem for linux definitely works with maws.

In trying to get it working under Git Bash mingw64, I could see that we could install mozilla-aws-cli-mozilla and mozilla-aws-cli, but maws didn't see the config available from mozilla-aws-cli-mozilla for some reason

Also, by default the WSL doesn't have ~/.local/bin in the PATH so that needed to be added.

In Git Bash mingw64 a PATH modification was also needed. We got the error

WARNING: The script maws.exe is installed in 'C:\Users\jdoe\AppData\Local\Packages\PythonSoftwareFoundation.Python.3.9_qbz5n2kfra8p0\LocalCache\local-packages\Python39\Scripts' which is not on PATH.