The SitePoint PHP blog has a tutorial posted showing you how to create multi-language documentation with ReadTheDocs and Sphinx with the help of the RTDSphinx-PHP library.

This post will guide you through getting up and running with RTDSphinx-PHP, a ReadTheDocs-friendly Sphinx based PHP documentation skeleton with sane defaults, pre-installed directives, and modified styles for optimal API and prose documentation rendering in multiple languages. For an unfinished example of the documentation, see here and switch the language in the bottom left flyout panel.

If this sounds familiar, it’s because we already went through a manual setup of a similar skeleton in a previous post, but that one had no localization support, too many steps, and wasn’t as reusable as this newly developed one.

He starts with the "quickstart" instructions to help you get the necessary tools installed to create the documentation. From there he gets into some of the main features the library provides including localization, a few utility scripts and syntax highlighting. Each of these comes with a bit of code/markup showing how to put them to use. The post ends with the instructions you'll need to push the documentation you've created up to ReadTheDocs and what the results should look like.