Consider mentioning mikepjb/vim-chruby on the vim wiki page

[k3rni]

https://github.com/mikepjb/vim-chruby is a de-facto rewrite of chruby in plain vim. It solves the problems people have (well, that I had) with chruby in vim: without it, the only way to make it work is to launch vim or nvim from a shell with chruby already loaded and paths set. Changing rubies while in vim does not work.

Vim-chruby adds a :Chruby command, mimicking the shell function to choose, and an auto mode.