docs(maintainers): add the new maintainer for MediaTek SoCs

Change-Id: Ia9409127e91e55726db0856e3f13f009d3c7c866
diff --git a/docs/about/maintainers.rst b/docs/about/maintainers.rst
index ad125cf..2a4d683 100644
--- a/docs/about/maintainers.rst
+++ b/docs/about/maintainers.rst
@@ -480,6 +480,8 @@
 ^^^^^^^^^^^^^^^^^^^^^^^
 :|M|: Rex-BC Chen <rex-bc.chen@mediatek.com>
 :|G|: `mtk-rex-bc-chen`_
+:|M|: Leon Chen <leon.chen@mediatek.com>
+:|G|: `leon-chen-mtk`_
 :|F|: docs/plat/mt\*.rst
 :|F|: plat/mediatek/
 
@@ -805,6 +807,7 @@
 .. _mmind: https://github.com/mmind
 .. _MrVan: https://github.com/MrVan
 .. _mtk-rex-bc-chen: https://github.com/mtk-rex-bc-chen
+.. _leon-chen-mtk: https://github.com/leon-chen-mtk
 .. _niej: https://github.com/niej
 .. _npoushin: https://github.com/npoushin
 .. _prabhakarlad: https://github.com/prabhakarlad