The documentation for this release can be found online at the XFree86 web site. Documentation for the latest release version can always be found here, and documentation for the latest pre-release snapshot can be found here.
Information about binary distributions and the attendant installation instructions can be found in the Installation Document.
The XFree86 version numbering system (including historical information) can be found in the Versions Document.
Additional information may be available at the XFree86 web site, and pointers to other information are available at the XFree86 support page.