According to @graywh's comment on:
Explicitly tell rbenv to use zsh
Basically without this change you will get the following error when enabling the rbenv plugin:
/Users/.../.rbenv/libexec/../completions/rbenv.bash:14: command not found: complete
@robbyrussell @dipth Does this mean if Im using the rbenv plugin I dont need to have eval "$(rbenv init - zsh)" in my .zshrc?
eval "$(rbenv init - zsh)"