Removes i686 from devtest doc
Removes i686 from devtest doc

Only amd64 is used in all script parameters, there is no need to mention
i686 => x86_64 replacement in devtest notes.

Change-Id: I80f3df0fe1e61c9db950c7263f09c53c132b5ed7

rdo-management/tripleo,rdo-management/tripleo