MINIFI-343 - Adding usage section to c2 README
MINIFI-343 - Adding usage section to c2 README

This closes #85.

Signed-off-by: Aldrin Piri <8746015474cd01110181ed51735247560fd08de4@apache.org>

apiri/nifi-minifi,apiri/nifi-minifi,apiri/nifi-minifi