docs/system: Briefly document canon-a1100 board

Add skeletal documentation of the canon-a1100 board.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Message-id: 20200713175746.5936-2-peter.maydell@linaro.org
diff --git a/MAINTAINERS b/MAINTAINERS
index 5d9c56e..9ed36dc 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -636,6 +636,7 @@
 F: hw/*/digic*
 F: include/hw/*/digic*
 F: tests/acceptance/machine_arm_canona1100.py
+F: docs/system/arm/digic.rst
 
 Goldfish RTC
 M: Anup Patel <anup.patel@wdc.com>