Documentation Request Summary:

Need to remove mentions of --enableMajorityReadConcern. In the release notes, mention that the parameter is deprecated and now has no effect, as MajorityReadConcern is now always enabled in 3.6.

Engineering Ticket Description:

--enableMajorityReadConcern should now have no effect (but not return an error). We can also eliminate the error that results from using this parameter on a storage engine that doesn't support snapshots.
Additionally, we can remove isMajorityReadConcernEnabled() from ReplSettings.