Fixed README with new instructions for generating manifest
Fixed README with new instructions for generating manifest

Signed-off-by: Fermin Ordaz <a119d26a2df8d897e236264b5f49339a5039ee4c@gmail.com>

cloudfoundry-incubator/cf-routing-release,cloudfoundry-incubator/cf-routing-release,cloudfoundry-incubator/cf-routing-release,fordaz/cf-routing-release,fordaz/cf-routing-release