rockchip: document platform

This adds a rockchip.rst to docs/plat documenting the general
approach to using the Rockchip ATF platforms together with the
supported bootloaders and also adds myself as maintainer after
making sure Tony Xie is ok with that.

Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Change-Id: Idce53d15eff4ac6de05bbb35d86e57ed50d0cbb9
diff --git a/maintainers.rst b/maintainers.rst
index 52c3dac..4bee64c 100644
--- a/maintainers.rst
+++ b/maintainers.rst
@@ -208,6 +208,8 @@
 :M: Tony Xie <tony.xie@rock-chips.com>
 :G: `TonyXie06`_
 :G: `rockchip-linux`_
+:M: Heiko Stuebner <heiko@sntech.de>
+:G: `mmind`_
 :F: plat/rockchip/
 
 STM32MP1 platform port
@@ -277,6 +279,7 @@
 .. _niej: https://github.com/niej
 .. _kostapr: https://github.com/kostapr
 .. _masahir0y: https://github.com/masahir0y
+.. _mmind: https://github.com/mmind
 .. _mtk09422: https://github.com/mtk09422
 .. _npoushin: https://github.com/npoushin
 .. _qoriq-open-source: https://github.com/qoriq-open-source