doc: sort net alphabetically

Reorders, with minimal contextual duplication, the net documentation alphabetically. PR-URL: nodejs#3662 Reviewed-By: Evan Lucas <evanlucas@me.com> Reviewed-By: James M Snell <jasnell@gmail.com> Reviewed-By: Jeremiah Senkpiel <fishrock123@rocketmail.com>

Author: tflanagan