doc: add Contributing to Node.js to the README ToC

PR-URL: #17106 Reviewed-By: Refael Ackermann <[email protected]> Reviewed-By: Luigi Pinca <[email protected]> Reviewed-By: Colin Ihrig <[email protected]> Reviewed-By: Gireesh Punathil <[email protected]> Reviewed-By: Michael Dawson <[email protected]>

Author: Trott

README.md

@@ -35,6 +35,7 @@ policies, and releases are managed under an
 *[TSC (Technical Steering Committee)](#tsc-technical-steering-committee)
 *[Collaborators](#collaborators)
 *[Release Team](#release-team)
+*[Contributing to Node.js](#contributing-to-nodejs)
 
 ## Support
 
@@ -578,7 +579,7 @@ Previous releases may also have been signed with one of the following GPG keys:
 ***Timothy J Fontaine**<[email protected]>
 `7937DFD2AB06298B2293C3187D33FF9D0246406D`
 
-###Contributing to Node.js
+## Contributing to Node.js
 
 *[Contributing to the project][]
 *[Working Groups][]