doc: update CHANGELOG.md for Node.js 16.13.0
Update missed changes for the main CHANGELOG.md for Node.js 16.13.0.
Refs: https://github.com/nodejs/node/pull/40536
I'll try to work out why the tooling missed these (the table heading at least is an inconsistency between escaping _
characters in the changelog links (escaped in markdown but not escaped in HTML)).