doc: add link to help repo in README

Include link to Node.js help repo (for end user questions on how to use
Node.js) in the README.

PR-URL: https://github.com/nodejs/node/pull/8570
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Teddy Katz <teddy.katz@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Сковорода Никита Андреевич <chalkerx@gmail.com>

README.md

@@ -21,6 +21,7 @@ If you need help using or installing Node.js, please use the
 ### Official Resources
 
 * [Website][]
+* [Node.js Help][]
 * [Contributing to the project][]
 * IRC (node core development): [#node-dev on chat.freenode.net][]
 
@@ -386,6 +387,7 @@ keys:
 
 [Website]: https://nodejs.org/en/
 [Contributing to the project]: CONTRIBUTING.md
+[Node.js Help]: https://github.com/nodejs/help
 [Node.js Moderation Policy]: https://github.com/nodejs/TSC/blob/master/Moderation-Policy.md
 [#node.js on chat.freenode.net]: https://webchat.freenode.net?channels=node.js&uio=d4
 [#node-dev on chat.freenode.net]: https://webchat.freenode.net?channels=node-dev&uio=d4