maintainers: add x807x

maintainers/maintainer-list.nix

···
     github = "x3rAx";
     githubId = 2268851;
   };
+  x807x = {
+    name = "x807x";
+    email = "[e-mail]";
+    matrix = "@x807x:matrix.org";
+    github = "x807x";
+    githubId = 86676478;
+  };
   xanderio = {
     name = "Alexander Sieg";
     email = "[e-mail]";