Maintainers: Add Ragnar Dahlen

lib/maintainers.nix

···
   pSub = "Pascal Wittmann <[e-mail]>";
   puffnfresh = "Brian McKenna <[e-mail]>";
   qknight = "Joachim Schiele <[e-mail]>";
+  ragge = "Ragnar Dahlen <[e-mail]>";
   raskin = "Michael Raskin <[e-mail]>";
   redbaron = "Maxim Ivanov <[e-mail]>";
   refnil = "Martin Lavoie <[e-mail]>";