doc: remove Roadmap Working Group

Refs: nodejs/CTC#16
PR-URL: #9545
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Evan Lucas <evanlucas@me.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Johan Bergström <bugs@bergstroem.nu>
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>
Reviewed-By: Roman Reiss <me@silverwind.io>

WORKING_GROUPS.md

@@ -24,7 +24,6 @@ back in to the CTC.
 * [Diagnostics](#diagnostics)
 * [i18n](#i18n)
 * [Evangelism](#evangelism)
-* [Roadmap](#roadmap)
 * [Docker](#docker)
 * [Addon API](#addon-api)
 * [Benchmarking](#benchmarking)
@@ -196,19 +195,6 @@ Responsibilities include:
 * Messaging about the future of HTTP to give the community advance notice of
   changes.
 
-### [Roadmap](https://github.com/nodejs/roadmap)
-
-The Roadmap Working Group is responsible for user community outreach
-and the translation of their concerns into a plan of action for Node.js.
-
-The final [ROADMAP](./ROADMAP.md) document is still owned by the TC and requires
-the same approval for changes as any other project asset.
-
-Their responsibilities are:
-* Attracting and summarizing user community needs and feedback.
-* Finding or potentially creating tools that allow for broader participation.
-* Creating Pull Requests for relevant changes to [ROADMAP.md](./ROADMAP.md)
-
 ### [Docker](https://github.com/nodejs/docker-iojs)
 
 The Docker Working Group's purpose is to build, maintain, and improve official