Fully document supported cache store interface.

README.md

@@ -470,10 +470,10 @@ It's a good idea, when relying on any external service, to cache retrieved data.
 
 This example uses Redis, but the cache store can be any object that supports these methods:
 
-* `store#[](key)`         - retrieves a value
-* `store#[]=(key, value)` - stores a value
-* `store#keys`            - lists all keys
-* `store#del(url)`        - deletes a value
+* `store#[](key)` or `#get` or `#read` - retrieves a value
+* `store#[]=(key, value)` or `#set` or `#write` - stores a value
+* `store#keys` - lists all keys
+* `store#del(url)` - deletes a value
 
 Even a plain Ruby hash will work, though it's not a great choice (cleared out when app is restarted, not shared between app instances, etc).