Fix slightly awkward English in Action Caching section of Caching With Rails guide.

In particular, removed "pages that require to restrict access somehow" and shortened "Action Caching works like Page Caching except for the fact that the incoming web request does go from the webserver to the Rails stack and Action Pack so that before filters can be run on it before the cache is served".

guides/source/caching_with_rails.textile

@@ -92,7 +92,7 @@ INFO: Page caching runs in an after filter. Thus, invalid requests won't generat
 
 h4. Action Caching
 
-One of the issues with Page Caching is that you cannot use it for pages that require to restrict access somehow. This is where Action Caching comes in. Action Caching works like Page Caching except for the fact that the incoming web request does go from the webserver to the Rails stack and Action Pack so that before filters can be run on it before the cache is served. This allows authentication and other restriction to be run while still serving the result of the output from a cached copy.
+Page Caching cannot be used for actions that have before filters - for example, pages that require authentication. This is where Action Caching comes in. Action Caching works like Page Caching except the incoming web request hits the Rails stack so that before filters can be run on it before the cache is served. This allows authentication and other restrictions to be run while still serving the result of the output from a cached copy.
 
 Clearing the cache works in a similar way to Page Caching, except you use +expire_action+ instead of +expire_page+.