Update ruby.plugin.zsh (#2117)

Added some Gem command shorthands, and ruby shorthand

plugins/ruby/ruby.plugin.zsh

@@ -4,3 +4,11 @@ alias sgem='sudo gem'
 
 # Find ruby file
 alias rfind='find . -name "*.rb" | xargs grep -n'
+
+# Shorthand Ruby
+alias rb="ruby"
+
+# Gem Command Shorthands
+alias gin="gem install"
+alias gun="gem uninstall"
+alias gli="gem list"