maintainers: add melvyn2

maintainers/maintainer-list.nix

···
     githubId = 15093162;
     name = "Melanie B. Sigl";
   };
+  melvyn2 = {
+    email = "[e-mail]";
+    github = "melvyn2";
+    githubId = 9157412;
+    name = "melvyn";
+    keys = [{
+      fingerprint = "232B 9F00 2153 CA86 849C  9224 25A2 B728 0CE3 AFF6";
+    }];
+  };
   mephistophiles = {
     email = "[e-mail]";
     name = "Maxim Zhukov";