Example: make ActiveRecords with RowGatewayFeature

The use of a prototype object as a constructor argument to RowGateway
is undocumented and very useful.
Merge pull request #803 from grncdr/patch-1

Example: make ActiveRecords with RowGatewayFeature
[#803] Added section marker

- and edited slightly
Merge branch 'hotfix/803'

Close #803