docs(naughty): fix broken link (#3749)

* docs(naughty): fix broken link

New GNOME developer documentation website
https://discourse.gnome.org/t/new-gnome-developer-documentation-website/7134

* docs(naughty): fix broken link

lib/naughty/core.lua

@@ -103,7 +103,7 @@ gtable.crush(naughty, require("naughty.constants"))
 
 --- The reason why a notification is to be closed.
 --
--- See [the specification](https://developer.gnome.org/notification-spec/#signals)
+-- See [the specification](https://specifications.freedesktop.org/notification-spec/notification-spec-latest.html#signals)
 -- for more details.
 --
 -- @table naughty.notification_closed_reason

lib/naughty/dbus.lua

@@ -39,7 +39,7 @@ local dbus = { config = {} }
 local bus_connection
 
 -- DBUS Notification constants
--- https://developer.gnome.org/notification-spec/#urgency-levels
+-- https://specifications.freedesktop.org/notification-spec/notification-spec-latest.html#urgency-levels
 local urgency = {
     low      = "\0",
     normal   = "\1",