Merge pull request #251 from fastruby/fix/omniref-dead-link

Replace dead omniref.com link with rubydoc.info docs

Author: JuanVqz

README.md

@@ -59,7 +59,7 @@ Idioms
 
 ##### `attr_accessor` vs `getter and setter` [code](code/general/attr-accessor-vs-getter-and-setter.rb)
 
-> https://www.omniref.com/ruby/2.2.0/files/method.h?#annotation=4081781&line=47
+> https://www.rubydoc.info/stdlib/core/Module:attr_accessor
 
 ```
 $ ruby -v code/general/attr-accessor-vs-getter-and-setter.rb