Add another example test that shows off self.assert_no_404_errors()

[mdmintz]

Add another example test that shows off self.assert_no_404_errors().

(Can add a new web page to seleniumbase.io with broken links for this.)

[mdmintz]

Resolved by #868 and shipped in https://github.com/seleniumbase/SeleniumBase/releases/tag/v1.60.0