Update README.md for LDAP documentation
Update README.md for LDAP documentation

Change-Id: I03f696bfac1df2cd91d02d02667b6d187180ad70
Signed-off-by: George Keishing <bef0a9ecac45fb57611777c8270153994e13fd2e@in.ibm.com>

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