doc: merge Working Groups with Contributing to Node.js in README

PR-URL: #17106
Reviewed-By: Refael Ackermann <refack@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>

Author: Trott

README.md

@@ -578,19 +578,16 @@ Previous releases may also have been signed with one of the following GPG keys:
 * **Timothy J Fontaine** <tjfontaine@gmail.com>
 `7937DFD2AB06298B2293C3187D33FF9D0246406D`
 
-### Working Groups
-
-Information on the current Node.js Working Groups can be found in the
-[TSC repository](https://github.com/nodejs/TSC/blob/master/WORKING_GROUPS.md).
-
 ### Contributing to Node.js
 
 * [Contributing to the project][]
+* [Working Groups][]
 
 [npm]: https://www.npmjs.com
 [Code of Conduct]: https://github.com/nodejs/TSC/blob/master/CODE_OF_CONDUCT.md
 [Contributing to the project]: CONTRIBUTING.md
 [Node.js Help]: https://github.com/nodejs/help
 [Node.js Website]: https://nodejs.org/en/
 [Questions tagged 'node.js' on StackOverflow]: https://stackoverflow.com/questions/tagged/node.js
+[Working Groups]: https://github.com/nodejs/TSC/blob/master/WORKING_GROUPS.md
 [#node.js channel on chat.freenode.net]: https://webchat.freenode.net?channels=node.js&uio=d4