nixos/bird: Fix doc compilation

Changed files
+1 -1
nixos
modules
services
networking
+1 -1
nixos/modules/services/networking/bird.nix
···
type = types.string;
description = ''
BIRD Internet Routing Daemon configuration file.
-
http://bird.network.cz/?get_doc&f=bird-3.html
+
<link xlink:href='http://bird.network.cz/'/>
'';
};