docs: Remove reference to Ruby

README.md

@@ -42,8 +42,6 @@ Install using one of the following methods:
 
 * Download directly from the [project page](https://github.com/JohnAlbin/normalize-scss/releases).
 * Install with [npm](http://npmjs.org/): `npm install --save normalize-scss`
-* Install with [Ruby Gem](https://rubygems.org/gems/normalize-scss): `gem install normalize-scss`<br>
-  and, optionally, add `require "normalize-scss"` to your config.rb file. Note: if you want to alter the _normalize.scss file after installation (see "how to use it" below), you can use the `gem list --details normalize-scss` command to show you where the normalize-scss files were installed.
 
 ## How to use it