adds description to gemspec

Author: xuanxu

rails_autolink.gemspec

@@ -5,7 +5,7 @@ Gem::Specification.new do |s|
   s.email = '[email protected]'
   s.homepage = 'https://github.com/tenderlove/rails_autolink'
   s.summary =  'Automatic generation of html links in texts'
-  s.summary = 'This is an extraction of the `auto_link` method from rails. The `auto_link` method was removed from Rails in version Rails 3.1. This gem is meant to bridge the gap for people migrating.'
+  s.description = 'This is an extraction of the `auto_link` method from rails. The `auto_link` method was removed from Rails in version Rails 3.1. This gem is meant to bridge the gap for people migrating.'
 
   s.add_dependency 'rails', '> 3.1'