Generating on online Users Guide like CI's

What do you mean "make your own"? Is it still there in 3.18, just not supported?

proof that an old dog can learn new tricks

The 2.2.6 version was strictly html not Sphinx and Python.

You just had to edit and change html files.

SEE: CodeIgniter 2.2.5 User Guide

Table of Contents / General Topics / Writing Documentation

There you can get the css and the template for creating the documentation.

What did you Try? What did you Get? What did you Expect?

Joined CodeIgniter Community 2009.  ( Skype: insitfx )

What do you mean "make your own"? Is it still there in 3.18, just not supported?

CodeIgniter Version 3.1.8 not 3.18

what is the problem with Sphinx?

Your suggestion is use Sphinx?

proof that an old dog can learn new tricks

If you use Sphinx then you will need to install Python also on your system.

What did you Try? What did you Get? What did you Expect?

Joined CodeIgniter Community 2009.  ( Skype: insitfx )

I found something called HelpnDoc that I am going to try which is free for personal projects.

https://www.helpndoc.com/feature-tour

proof that an old dog can learn new tricks