Correct documentation for Couchnode constructor.

Change-Id: I1834339ba1e057b814bfd26444173a634e187cdc
Reviewed-on: http://review.couchbase.org/28707
Reviewed-by: Matt Ingenthron <matt@couchbase.com>
Reviewed-by: Brett Lawson <brett19@gmail.com>
Tested-by: Brett Lawson <brett19@gmail.com>