module: remove :tools rgb

This module has been deprecated for some time; it's too niche, too
trivial, and is mostly centered around a single hydra (official support
for which I'll be phasing out of Doom).

templates/init.example.el

@@ -102,7 +102,6 @@
        ;;pass              ; password manager for nerds
        ;;pdf               ; pdf enhancements
        ;;prodigy           ; FIXME managing external services & code builders
-       ;;rgb               ; creating color strings
        ;;taskrunner        ; taskrunner for all your projects
        ;;terraform         ; infrastructure as code
        ;;tmux              ; an API for interacting with tmux