Match rbenv init line to thoughtbot/dotfiles
Match rbenv init line to thoughtbot/dotfiles

`append_to_zshrc` checks whether the substring is in
`~/.zshrc` or `~/.zshrc.local`.
If it isn't, it appends it.

https://github.com/thoughtbot/dotfiles/blob/master/zsh/configs/post/path.zsh

iphilgood/laptop