update model documentation (#783)
update model documentation (#783)


chingor13/google-cloud-php,jdpedrie/google-cloud-php,jdpedrie/google-cloud-php,chingor13/google-cloud-php,googleapis/google-cloud-php,googleapis/google-cloud-php,jdpedrie/google-cloud-php,googleapis/google-cloud-php,chingor13/google-cloud-php