Git setup/identity/config

[MichelleBlanchette]

Notes about git config --global and git config --local for setting identity like user.name and user.email.

Also note about changing the author of a commit by performing an interactive rebase, git rebase -i HEAD~n with edit <commit>... and git rebase --amend --author="Michelle Blanchette <michelle@purpleturtlecreative.com>" --no-edit and then git rebase --continue.

[MichelleBlanchette]

Would also be nice if you could document the config credential.helper=store for securely storing git credentials for like GitHub password/PAT so that I have the complete setup process documented.