Documentation Guidelines
QGIS Documentation is available at https://docs.qgis.org. As the writing process is going on, a build is automatically run every day (see bottom of the page for exact time) for all supported versions (testing, Long Term Release (LTR) and next-to-be LTR).
QGIS Documentation source files are available at https://github.com/qgis/QGIS-Documentation. They are mainly written using the reStructuredText (reST) format syntax, coupled with some scripts from the Sphinx toolset to post-process the HTML output.
The following chapters will guide you through learning:
how to manage the documentation source files using git system and the GitHub platform on which they are stored
how to modify the texts, provide screenshots… in a compliant way
how to share and ensure your modifications are pushed to the official docs.
If you are looking for general information about how to contribute to the QGIS project, you may find help at Get Involved in the QGIS Community.