fs,doc: use `target` instead of `destination`

PR-URL: https://github.com/nodejs/node/pull/3912


Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Evan Lucas <evanlucas@me.com>
Reviewed-By: Michaël Zasso <mic.besace@gmail.com>
Reviewed-By: Bert Belder <bertbelder@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>