maintainers: add jacg

maintainers/maintainer-list.nix

@@ -2808,6 +2808,11 @@
     githubId = 26877687;
     name = "Yurii Izorkin";
   };
+  jacg = {
+    name = "Jacek Generowicz";
+    email = "jacg@my-post-office.net";
+    githubId = "2570854";
+  };
   jasoncarr = {
     email = "jcarr250@gmail.com";
     github = "jasoncarr0";