Create `git is-repo` and `git ref`
Create `git is-repo` and `git ref`

is-repo will be based on is_git_repo in .zshrc. ref will be based on
git_ref in .zshrc. By having them as git aliases rather than zsh
functions, they'll be more flexible and can be used from anywhere,
whereas the zsh functions require an interactive zsh shell.

Also rename the section "Branches" to "Where am I?". is-repo and ref
don't really fit into any other section as well, and the name change
fits them and aliases already in there.

joeljk13/dotfiles,joeljk13/dotfiles