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: nodejs#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>

doc/api/debugger.md

@@ -190,8 +190,8 @@ V8 Inspector can be enabled by passing the `--inspect` flag when starting a
 Node.js application. It is also possible to supply a custom port with that flag,
 e.g. `--inspect=9222` will accept DevTools connections on port 9222.
 
-To break on the first line of the application code, provide the `--debug-brk`
-flag in addition to `--inspect`.
+To break on the first line of the application code, pass the `--inspect-brk`
+flag instead of `--inspect`.
 
 ```txt
 $ node --inspect index.js