doc: update V8 debugger doc to mention --inspect-brk

Node now supports the `--inspect-brk` flag, which does the same thing
as `--inspect --debug-brk`. One thing that's nice about the new flag is
that it uses "inspect" language -- this is a suggested update to the
docs.

PR-URL: https://github.com/nodejs/node/pull/11495


Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Gibson Fahnestock <gibfahn@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Josh Gavant <josh.gavant@outlook.com>
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>