doc: revise Collaborator Nominations introduction

Revise the introductory paragraphs for Collaborator Nominations in
GOVERNANCE.md. This change splits long and unnecessarily complex
sentences into multiple simple statements.

PR-URL: #27237
Reviewed-By: Anatoli Papirovski <apapirovski@mac.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>

GOVERNANCE.md

@@ -109,12 +109,12 @@ the issue tracker is:
 
 ## Collaborator Nominations
 
-Any existing Collaborator can nominate an individual making significant
-and valuable contributions across the Node.js organization to become a new
-Collaborator.
+Existing Collaborators can nominate someone to become a Collaborator. Nominees
+should have significant and valuable contributions across the Node.js
+organization.
 
-To nominate a new Collaborator, open an issue in the [nodejs/node][]
-repository, with a summary of the nominee's contributions, for example:
+To nominate a new Collaborator, open an issue in the [nodejs/node][] repository.
+Provide a summary of the nominee's contributions. For example:
 
 * Commits in the [nodejs/node][] repository.
   * Can be shown using the link