Add note about Rails 4.1 and ActiveRecord `count`.

README.md

@@ -13,6 +13,12 @@ Compatibility
 * Works very well outside of Rails, you just need to install either the `json` (for MRI) or `json_pure` (for JRuby) gem.
 
 
+Rails 4.1 Note
+--------------
+
+Due to [a change in ActiveRecord's `count` method](https://github.com/rails/rails/pull/10710) you will need to use `count(:all)` to explicitly count all columns ("*") when using a `near` scope. Using `near` and calling `count` with no argument will cause exceptions in many cases.
+
+
 Installation
 ------------