ciao-cert: hostname clarifications for README.md
ciao-cert: hostname clarifications for README.md

We're seeing users not understanding the implications of hostnames in
certificates.  This commit attempts to be more explicit about the security
trade offs and the deployment choices for generic keys versus machine
specific keys.

Signed-off-by: Tim Pepper <8dbd764830e941d092a1cb7fa16423169acc0b04@linux.intel.com>

01org/ciao,erick0z/ciao,rbradford/ciao,tpepper/ciao,obedmr/ciao,mcastelino/ciao,wcwxyz/ciao,mcastelino/ciao,01org/ciao,erick0z/ciao,mrkz/ciao,obedmr/ciao,rbradford/ciao,ciao-project/ciao,matthewrsj/ciao,tpepper/ciao,matthewrsj/ciao,mcastelino/ciao,mrkz/ciao,matthewrsj/ciao,markdryan/ciao,wcwxyz/ciao,kaccardi/ciao,erick0z/ciao,markdryan/ciao,ciao-project/ciao,tpepper/ciao,wcwxyz/ciao,mrkz/ciao,kaccardi/ciao,obedmr/ciao