boards: amlogic: update documentation for WeTek Core2

Update the device matrix and add build instructions.

Signed-off-by: Christian Hewitt <christianshewitt@gmail.com>
[narmstrong: added wetek-core2.rst to q200 MAINTAINERS and added blank lines to fix build]
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
3 files changed