tc: Update README and add config

Updated README.

Added config file that contains the minimum required features enabled to
run the tests currently present in the kernel.
This must be updated when new unittests are created and require their own
modules.

Signed-off-by: Keara Leibovitz <kleib@mojatatu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>