doc: add Malte-Thorben Bruns to .mailmap

PR-URL: #1118
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>

Author: bnoordhuis

.mailmap

@@ -70,6 +70,8 @@ Kris Kowal <kris.kowal@cixar.com>
 Kyle Robinson Young <kyle@dontkry.com>
 Luke Bayes <lbayes@patternpark.com>
 Maciej Małecki <maciej.malecki@notimplemented.org> <me@mmalecki.com>
+Malte-Thorben Bruns <skenqbx@gmail.com>
+Malte-Thorben Bruns <skenqbx@googlemail.com>
 Mathias Pettersson <mape@mape.me>
 Michael Bernstein <michaelrbernstein@gmail.com>
 Michael Wilber <gcr@sneakygcr.net>