doc: claim ABI version for Electron v15 and v16

PR-URL: https://github.com/nodejs/node/pull/39950


Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Richard Lau <rlau@redhat.com>
Reviewed-By: Shelley Vohr <shelley.vohr@gmail.com>
Reviewed-By: Jiawen Geng <technicalcute@gmail.com>