doc: claim NODE_MODULE_VERSION=76 for Electron 8

PR-URL: https://github.com/nodejs/node/pull/28809
Refs: https://github.com/electron/electron/projects/20#card-24099810


Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>