This repo is the source behind http://docs.syncthing.net/.
To edit the documentation you need a GitHub account. Once you have created one and logged in, you can edit any page by navigating to the corresponding file and clicking the edit (pen) icon. This will create a so called "fork" and a "pull request", which will be approved by one of the existing documentation team members. Once you have made a contribution or two, you can be added to the documentation team and perform edits without requiring approval.
In the long run, learning to use Git and running Sphinx on your computer is beneficial.
The documentation is divided into an index page (index.rst) and various
subsections. The sections are:
- Introductory information in
intro. - Information for users in
users. - Information for developers in
dev.
The documentation uses the rst format. For a starting point check out the reStructuredText Primer