Why does this lesson even talk about irregular verbs, since the title is "regular verbs"?

This is the first lesson I've run across that is confusing, so that's pretty darn good!  There are no examples of third person plural except the irregular one, so a novice has no idea what the third person plural rule is for regular verbs.  Please update so make it clear that aient is indeed the ending for regular as well as irregular verbs (maybe by using a regular verb as the example since this page is supposed to be about regular verbs).  Thanks.