Make clearer what automatic view update options can be set at the design doc level

See MB-11594 a customer would like to set the updateinterval setting per design document, the documentation hints this is possible but it isn't. The documentation isn't explicit which settings (updateInterval, updateMinChanges, replicaUpdateMinChanges) can be set per design document vs what is set at the system level. http://docs.couchbase.com/couchbase-manual-2.5/cb-admin/#automated-index-updates

"To configure the update values explicitly on individual design documents, you must...."

This needs to be changed to

"To configure the updateMinChanges or replicaUpdateMinChanges values explicitly on individual design documents, you must...."