board: amlogic: add board doc files to MAINTAINERS

Add the recently added reStructuredText board documentation in the
appropriate MAINTAINERS files.

Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
diff --git a/board/amlogic/q200/MAINTAINERS b/board/amlogic/q200/MAINTAINERS
index 6f00f87..ec05aa6 100644
--- a/board/amlogic/q200/MAINTAINERS
+++ b/board/amlogic/q200/MAINTAINERS
@@ -7,3 +7,4 @@
 F:	configs/khadas-vim2_defconfig
 F:	configs/libretech-s905d-pc_defconfig
 F:	configs/libretech-s912-pc_defconfig
+F:	doc/board/amlogic/khadas-vim2.rst