Add pip usage hint for mac users

[oberstet]

Mac is (nowerdays) using zsh per default (previously it was bash)

Starting with macOS Catalina (v10.15 anno Oktober 2019), your Mac uses zsh as the default login shell and interactive shell.

https://support.apple.com/en-ca/HT208050

which has fancy command line name globbing that interferes with pip

mu-editor/mu#852
http://zsh.sourceforge.net/Guide/zshguide05.html#l137

Solution for mac users is to do:

pip install "autobahn[all]"

or

pip install -e ."[all]"

[oberstet]

interesting .. there seems to be agreement that actually pip intall -e ".[all" is the way to go mu-editor/mu#852 (comment) :

• linux: works on bash and csh
• macos: works on zsh
• windows: works on powershell and cmd.exe

it should work on the BSDs as well ...