Is this ok as a description? I don't think the term display server is commonly used for wayland compositors, so I left the synopsis.
(description "Weston is the reference implementation of a Wayland compositor, and a useful compositor in its own right. A Wayland compositor allows applications to render to a shared offscreen buffer using opengles. The compositor then culls the hidden parts and composes the final output. A Wayland compositor is essentially a multiplexer to the KMS/DRM kernel devices.") I renamed xwayland to xorg-server-xwayland and added cairo-xcb to gtk.scm, xorg-server-xwayland to xorg.scm and weston to freedesktop.scm.