add stream as iterator part

[bertho-zero]

It would be useful to document this way of consuming streams.

[yagop]

Bumping this

[bertho-zero]

@OlivierCavadenti The comment, which is copied from the node doc, is not true with Knex, the basic functioning of the stream is altered.

If I break in the loop without destroy then the knex connection stays open.

The following destroy should be called automatically on a break:
https://github.com/knex/knex/blob/7c819d325cce1e4c364d0639e1228955d3b662db/test/integration2/query/misc/additional.spec.js#L160