The documentation links for thunar-volman at
are broken and redirect to XFCE's home page.
The Thunar link at the top of the page ( http://thunar.xfce.org ) is also broken and leads to XFCE's home page.
The documentation for thunar-volman is now available, but I guess it's very outdated...
Regarding thunar.xfce.org redirecting to xfce.org, this should be handled in bug #10554.