style(rbfu): clean up code

plugins/rbfu/README.md

@@ -4,6 +4,7 @@ This plugin starts [rbfu](https://github.com/hmans/rbfu), a minimal Ruby version
 manager, and adds some useful functions.
 
 To use it, add `rbfu` to the plugins array in your zshrc file:
+
 ```zsh
 plugins=(... rbfu)
 ```