doc: fix multiline return comments in querystring

Changes the multiline return example commments in querystring
which have the example out-of-comment, into single comment
lines to remain consistent with other docs.

PR-URL: https://github.com/nodejs/node/pull/5705


Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Sakthipriyan Vairamani <thechargingvolcano@gmail.com>