Merge pull request rust-lang#2434 from rust-lang/tshepang-mailmap

update surname (was lekhonkhobe previously) and email

Author: Noratrieb

src/doc/rustc-dev-guide/.mailmap

@@ -3,3 +3,4 @@ Jynn Nelson <github@jyn.dev> <joshua@yottadb.com>
 Jynn Nelson <github@jyn.dev> <jyn.nelson@redjack.com>
 Jynn Nelson <github@jyn.dev> <jnelson@cloudflare.com>
 Jynn Nelson <github@jyn.dev>
+Tshepang Mbambo <hopsi@tuta.io> <tshepang@gmail.com>