doc: move AndreasMadsen to emeritus

In private email, Andreas Madsen indicated it would be OK to move him to
emeritus.

PR-URL: https://github.com/nodejs/node/pull/39315


Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>