notification: Replace gnome spec page for fdo

The gnome one goes nowhere.

Dependencies.md

@@ -8,7 +8,7 @@
 * [GLib 2, Gio 2](http://www.gtk.org/) (>= 2.32) (GI bindings)
 * [GTK+ 3](http://www.gtk.org/) (>= 3.24) (GI bindings)
 * [gnome-icon-theme](https://git.gnome.org/browse/adwaita-icon-theme/), [mate-icon-theme](https://github.com/mate-desktop/mate-icon-theme), [adwaita-icon-theme](https://github.com/GNOME/adwaita-icon-theme), [elementary-xfce](https://github.com/shimmerproject/elementary-xfce), or [Papirus](https://github.com/PapirusDevelopmentTeam/papirus-icon-theme)
-* [notification-daemon](https://developer.gnome.org/notification-spec/) that provides dbus name org.freedesktop.Notifications
+* [notification-daemon](https://specifications.freedesktop.org/notification-spec/notification-spec-latest.html) that provides dbus name org.freedesktop.Notifications
 * [obexd 5](http://www.bluez.org/)
 * [Pango](http://www.gtk.org/) (GI bindings)
 * [pulseaudio](http://www.freedesktop.org/wiki/Software/PulseAudio/) (optional; its bluetooth module is required to actually use audio devices)