Clean up training manual metadata
Clean up training manual metadata

- removes authors, that is not a convention and there may be legal
ramifications
- fixes typo in the doc history

backport:havana

Change-Id: I3081d00195797a8ceef82350ce425c74750a9c81

harrisonfeng/training-guides,harrisonfeng/training-guides,harrisonfeng/training-guides,Nabs007/training-guides,Nabs007/training-guides,openstack/training-guides,Nabs007/training-guides,openstack/training-guides