Update IoTivity-Constrained's README
Update IoTivity-Constrained's README

Change-Id: I6545fc1ab876a5ed4e1eeaa14d27b4732038f68e
Signed-off-by: Kishen Maloor <c62ddea3cd661a9268bff15f07fc2229cdc9ac02@intel.com>
Reviewed-on: https://gerrit.iotivity.org/gerrit/12777

iotivity/iotivity-constrained,iotivity/iotivity-constrained,iotivity/iotivity-constrained,iotivity/iotivity-constrained