doc: move sebdeckers to emeritus

Confirmed in email with sebdeckers that they can be moved to emeritus.

PR-URL: https://github.com/nodejs/node/pull/34298


Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>