Minor updates

[ChristopherA]

• zsh requires space after bang
• M1 macOS has brew in different path, use brew --prefix
• Move Setup Git section to AFTER gpg section
• Configure git user.name & user.email from GPG key

[ChristopherA]

@namcios this is a relatively untested PR for your review, based on some learning while working on my own script ./macOS_GitHub_SSH_GPG_setup.sh at https://gist.github.com/ChristopherA/5740eb90e2875832d9c707b49b3b89a7

I've also been working on ./macOS_basic_setup.sh that can be curl | zsh at https://gist.github.com/ChristopherA/07fc2e4b962d3d894b0d3527c3f3923e that may give you some ideas.

Feel free to merge if it all tests ago, or close if you want to incorporate these changes in another PR.

[namcios]

Thanks for the updates. It looks good to me, I'll just test it on a VM before merging. I also want to add some logic and snippets from your Gist. (Especially on the M1 vs Intel parts, though I currently cannot test M1 stuff myself.)

Just curious on one thing, is the reason Git config comes after GPG config to relieve the user from typing name and email twice or are there other theoretical reasons for that order?

[ChristopherA]

The reason for moving it later was to eliminate the requirement to enter name & email if you already have gpg key on GitHub. Thus gh auth login gives you file with GitHub user name, which gives you name and email if you have gpg key.