unstable/xdg-decoration: Fix misleading description of configure
As found out in the thread https://gitlab.gnome.org/GNOME/gtk/-/merge_requests/6161#note_1781172 the wording of zxdg_toplevel_decoration_v1.configure is misleading, and it is an oversight, confirmed at https://gitlab.gnome.org/GNOME/gtk/-/merge_requests/6161#note_1781172 Fix it so that it does not confuse implementers.
Signed-off-by: Mikhail Gusarov dottedmag@dottedmag.net