maintainers: add cbleslie

maintainers/maintainer-list.nix

···
     matrix = "@cawilliamson:nixos.dev";
     name = "Christopher A. Williamson";
   };
+  cbleslie = {
+    email = "[e-mail]";
+    github = "cbleslie";
+    githubId = 500963;
+    name = "C.B.Leslie";
+  };
   cbley = {
     email = "[e-mail]";
     github = "avdv";