README: update device dictionary presentation
README: update device dictionary presentation

This updates the device dictionary presentation because of the moving of device
dictionaries to lib/device_map.py and the adding of kernel_defconfig_blacklist
array.

Signed-off-by: Quentin Schulz <222e928ffea5b2038b4ed3e727cfc6ce1f518a39@free-electrons.com>

kernelci/lava-ci-staging,kernelci/lava-ci-staging,kernelci/lava-ci-staging