guide: fix outdated section in debugging guide (#4732)

This removes `localhost6` from the domains that Node.js
accepts in connections to the debugging inspector. It
was removed due to being vulnerable to DNS rebinding
attacks.

See CVE-2021-22884 for more details.

Co-authored-by: Rich Trott <rtrott@gmail.com>
Co-authored-by: Rafael Gonzaga <rafael.nunu@hotmail.com>

Author: 3 people

locale/en/docs/guides/debugging-getting-started.md

@@ -59,7 +59,7 @@ unique debugger session id. The same-origin-policy prevents websites from being
 able to make this HTTP connection. For additional security against
 [DNS rebinding attacks](https://en.wikipedia.org/wiki/DNS_rebinding), Node.js
 verifies that the 'Host' headers for the connection either
-specify an IP address or `localhost` or `localhost6` precisely.
+specify an IP address or `localhost` precisely.
 
 These security policies disallow connecting to a remote debug server by
 specifying the hostname. You can work-around this restriction by specifying