Write documentation for Spring 3.0 new annotations [SPR-5455]

**[Michael Isvy](https://jira.spring.io/secure/ViewProfile.jspa?name=michael.isvy)** opened **[SPR-5455](https://jira.spring.io/browse/SPR-5455?redirect=false)** and commented

Create documentation for `@PathVariable`, `@RequestHeader`, `@CookieValue`


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No further details from [SPR-5455](https://jira.spring.io/browse/SPR-5455?redirect=false)