Minor suggestion for the Form validation tutorial

[Wail75]

Hello,

I have a minor suggestion for the Form validation tutorial: make it clear that $v->required('field') is valid even for empty values. I couldn't see it in the tutorial, even the doc for this method does not seem to say that https://docs.mojolicious.org/Mojolicious/Validator/Validation#required

I am only saying that because I lost some time trying to understand why something like $v->required('field')->range(1,10) was sending me errors about the range, with an empty value, rather a 'required' error. I found the answer only reading about the 'not_empty' check https://docs.mojolicious.org/Mojolicious/Validator/#not_empty

[daleif]

I agree, have gotten bit by that one my self. But got caught in unit testing.