depends.py documentation fixes
depends.py documentation fixes

Now that the format of exclusive groups has been changed,
update the documentation using it too.

Signed-off-by: Andrzej Kurek <f4c472ffe6ee3dcd17a8925cef48ace45ab528e9@arm.com>

ARMmbed/mbedtls,Mbed-TLS/mbedtls,ARMmbed/mbedtls,ARMmbed/mbedtls,Mbed-TLS/mbedtls,ARMmbed/mbedtls,Mbed-TLS/mbedtls,Mbed-TLS/mbedtls