Fix typo in readme

Author: mikebronner

README.md

@@ -2,7 +2,7 @@
 
 ## Features
 - automatic relationship caching.
-- automatic cache flushing when models are change.
+- automatic cache flushing when models are changed.
 - automatic use of cache flags for cache providers that support them (will flush
   entire cache for providers that don't).
 - provides simple caching methods for use in query methods for models that take