ApplicationMaker
This Mathematica package facilitates the integration of notebooks to the Documentation Center. This project was created to answer a question in stackoverflow.
Simply install the extracted zip into SystemOpen@FileNameJoin[{$UserBaseDirectory, "Applications"}].
The are two answers provided by myself in the question, the first one provides a lengthly explanation on how to do it manually.
The second one provides
ApplicationMaker.
Don't hesitate to contact me if you would like to contribute to this project.