maintainers: add cpcloud to maintainer-list.nix

maintainers/maintainer-list.nix

···
     github = "ymeister";
     githubId = 47071325;
   };
+  cpcloud = {
+    name = "Phillip Cloud";
+    email = "[e-mail]";
+    github = "cpcloud";
+    githubId = 417981;
+  };
 }