maintainers: add smitop

maintainers/maintainer-list.nix

···
     githubId = 4477729;
     name = "Sergey Mironov";
   };
+  smitop = {
+    name = "Smitty van Bodegom";
+    email = "[e-mail]";
+    matrix = "@smitop:kde.org";
+    github = "Smittyvb";
+    githubId = 10530973;
+  };
   sna = {
     email = "[e-mail]";
     github = "s-na";