mongodb/docs — pull request #1516 by devkev (2014-01-09 07:37:28+00:00)
Title: Clarify the need to specify priority: 0 for hidden secondaries

I found the previous wording suggestive that priority: 0 would be implied if not specified when hidden: true. I prefer this wording, as I feel it makes clearer the need for priority: 0 to be explicitly specified (even though it's not much of a change).