I like to keep my finger on the pulse with Apple products as well as with their documentation. Apple makes this easy with offering mailing lists that are dedicated to all their products. If you want to keep up specifically with all new and changed documentation, Apple has a great list for you: Daily Knowledge Base changes.
Apple’s description of the list:
“The Daily Knowledge Base changes mailing list announces new and modified documents in the AppleCare Knowledge Base. Each e-mail contains the titles of new and modified documents with links to them. E-mail from this list may also contain hints and tips to get the most out of your Apple products with links to Apple Discussions, Customer Installable Parts, custom support pages, and more.”
So if you want to make sure you keep up to date, subscribe to the list, it is low volume and very helpful!