Previous versions of Cocos2D were distributed only in the form of archive, which you needed to download, unpack, and run the install script from the console. Now, there is an installer and this is much more convenient, especially if you have never worked with a console.
However, although the installer is convenient, it makes it impossible to review the contents of Cocos2D distribution, which previously was automatically at your disposal when you unpacked the archive.
Of course, there is still a way to review it. You can download it on the same page where you downloaded the installer (http://www.cocos2d-iphone.org/download), but select Cocos2D zip archive 3.0.0 this time, or if you downloaded the book's supporting files, you can find it in the Chapter_02/cocos2d-iphone-v3.0-distribution folder.
Most of the items in the Cocos2D distribution are self-explanatory, but the following are a few items I should mention separately: