Added note about @deprecated annotation format

Refs https://github.com/cakephp/cakephp/pull/4463 and https://github.com/cakephp/cakephp/pull/4417#discussion_r16990677 respectively.
The link should point to the latest version of phpdoc manual http://phpdoc.org/docs/latest/references/phpdoc/tags/deprecated.html and format should say `@deprecated <version> <description>`.

All other links should also be updated to latest version of phpdoc manual.