Removed meta_search from installation instruction

Bundler will properly resolve the required version
of meta_search now that 1.1.0 is released.

README.rdoc

@@ -33,12 +33,11 @@ on Rails 3 application. To install, simply add the following to your Gemfile:
   # Gemfile in Rails < 3.1
   gem 'activeadmin'
 
-If you are using Rails >= 3.1, you must also include a beta version of MetaSearch and sass-rails:
+If you are using Rails >= 3.1, you must also have sass-rails in your Gemfile:
 
   # Gemfile in Rails >= 3.1
   gem 'activeadmin'
   gem 'sass-rails'
-  gem "meta_search",    '>= 1.1.0'
 
 After updating your bundle, run the installer