Improve README's CredHub section [#156104887]
Improve README's CredHub section [#156104887]

Signed-off-by: Iryna Shustava <2d2404266b0a0832518fb8eeb9ad53e987c2cdbe@pivotal.io>

cloudfoundry/cf-deployment,emalm/cf-deployment,cloudfoundry/cf-deployment