2.1.2.1 Cookies: note on other storage mechanisms

[ysmartin]

Suggestion: add this note to cookie feature (or add it as a new feature?)

Note: websites may use other mechanisms to store data in the client. These include HTTP-native mechanisms such as ETags (which sometimes work as a kind of cookie), HTML5 provides Web Storage, SQL Database, Indexed Database, and storage mechanisms provided by specific plugins such as Flash or Silverlight.

Rationale: website developers ("bad guys") often employ these mechanisms as complementary to cookies. Besides, HTML5 storage mechanisms are necessary to test the functionality of some modern web web applications that make use of that technology.