meta: improve definition of a collaborator

Expand definition of Collaborator to include individuals
with commit access to any Node.js GitHub repository.

Clarify the kinds of things that should be considered when
considering inviting new collaborators

PR-URL: #14981
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Evan Lucas <evanlucas@me.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Refael Ackermann <refack@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>
Reviewed-By: Yuta Hiroto <hello@about-hiroppy.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

Author: jasnell

GOVERNANCE.md

@@ -9,9 +9,21 @@ The [nodejs/node](https://github.com/nodejs/node) GitHub repository is
 maintained by Collaborators who are added by the CTC on an ongoing basis.
 
 Individuals identified by the CTC as making significant and valuable
-contributions are made Collaborators and given commit access to the project. If
-you make a significant contribution and are not considered for commit access,
-log an issue or contact a CTC member directly.
+contributions across any Node.js repository may be made Collaborators and given
+commit access to the project. Activities taken into consideration include (but
+are not limited to) the quality of:
+
+* code commits and pull requests
+* documentation commits and pull requests
+* comments on issues and pull requests
+* contributions to the Node.js website
+* assistance provided to end users and novice contributors
+* participation in Working Groups
+* other participation in the wider Node.js community
+
+If individuals making valuable contributions do not believe they have been
+considered for commit access, they may log an issue or contact a CTC member
+directly.
 
 Modifications of the contents of the nodejs/node repository are made on
 a collaborative basis. Anybody with a GitHub account may propose a