docs: fix streams example for write() after end()

Currently there's an example using http.ServerResponse stream, which
has a known bug and will not throw an error while writing after end().
Changed to a writable stream from fs which behaves as expected.

fix #8814

Signed-off-by: Julien Gilli <julien.gilli@joyent.com>
Merge remote-tracking branch 'upstream/v0.10' into v0.10