cakephp/docs — pull request #2067 by ravage84 (2014-12-01 11:32:16+00:00)
Title: Add Contributing to the PDF version of the book

The 3.x version of the book also has the Contributing section:
https://github.com/cakephp/docs/blame/66cc98a8775ceb67f627d4f3f54f1b3215e51f0e/en/pdf-contents.rst#L11

I see no reason not to include it.
There are valuable ressources such as the coding standard.