Update README.md deprecating legacy REST
Update README.md deprecating legacy REST

Change-Id: If9cc1d9459c5fb06ebfc260dfe80b2bc35f0fe1e
Signed-off-by: George Keishing <bef0a9ecac45fb57611777c8270153994e13fd2e@in.ibm.com>

openbmc/openbmc-test-automation,openbmc/openbmc-test-automation