Authoring guidelines for an Antora project compatible with modular documentation

The example defines an unique module: user-guide.

Optionally, rename it. Do not use the default ROOT module name, always use a Named Module Directory.

Optionally, add a module directory, create the required subdirectories and navigation file, and add the navigation file to the antora.yml file. See Antora - Standard File and Directory Set.

Use a consistent system for file names, IDs, and titles. See File Names and Anchors.