The Sphinx tool produces very good-looking documentation in a variety of formats. It can easily combine documentation from source code as well as external files with additional design notes, requirements, or background.
The Sphinx tool can be found at http://sphinx-doc.org. The download can become complex because Sphinx depends on several other projects. The Sphinx tutorial is outstanding.
Most projects will start by using sphinx-quickstart to create the initial set of files. Once the files are available, details can be added. To finalize the documentation, the sphinx-build program will be used.
Often, running sphinx-build is handled via the make program, which slightly simplifies the command-line use of Sphinx. In some cases, make may not be available.
- macOS users won't have make available by default. It's part of the XCode...
