doc: update who to cc for n-api

Add info about who to @cc for issues with n-api

PR-URL: https://github.com/nodejs/node/pull/13335


Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Jason Ginchereau <jasongin@microsoft.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Evan Lucas <evanlucas@me.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Gibson Fahnestock <gibfahn@gmail.com>
Reviewed-By: Hitesh Kanwathirtha <digitalinfinity@gmail.com>