Use RFC 2606 TLDs for documentation and tests

[Uzlopak]

https://datatracker.ietf.org/doc/html/rfc2606

To safely satisfy these needs, four domain names are reserved as
listed and described below.

               .test
            .example
            .invalid
          .localhost

  ".test" is recommended for use in testing of current or new DNS
  related code.

  ".example" is recommended for use in documentation or as examples.

  ".invalid" is intended for use in online construction of domain
  names that are sure to be invalid and which it is obvious at a
  glance are invalid.

  The ".localhost" TLD has traditionally been statically defined in
  host DNS implementations as having an A record pointing to the
  loop back IP address and is reserved for such use.  Any other use
  would conflict with widely deployed code which assumes this use.

Basically avoid using domains like example.com etc..