Documentation is a critical part of PEAR. Even the most interesting and helpful package will not be used without proper documentation that helps users understand it.
Documentation for a package in PEAR means two things:
API documentation that explains all classes, methods and functions a package provides
Chapters and paragraphs about the package itself: What the package can be used for, how to use it, and examples.
API documentation is automatically generated after a package has been released on pear.php.net from the code using phpDocumentor.
The second type of documentation needs to be created manually. It is the documentation you see in this very manual below the packages book.