Adding @0x4A6F to maintainers.nix (#34984)

* Adding @0x4A6F to maintainers.nix

* Removing decimal from handle

* Convert handle from Hex to ASCII

lib/maintainers.nix

···
   jirkamarsik = "Jirka Marsik <[e-mail]>";
   jlesquembre = "José Luis Lafuente <[e-mail]>";
   jluttine = "Jaakko Luttinen <[e-mail]>";
+  Jo = "Joachim Ernst <[e-mail]>";
   joachifm = "Joachim Fasting <[e-mail]>";
   joamaki = "Jussi Maki <[e-mail]>";
   joelmo = "Joel Moberg <[e-mail]>";