More control over checks (especially html)

[masafum...@gmail.com]

Hi, I'm new to Nanoc and I have a proposal about check configuration.

Currently I host my website on Netlify and it allows us to add `netlify` attribute to form tag so that users can submit a form to Netlify.

However, since it's not HTML compatible attribute (they process it during build time), Nanoc check detects it as an error.

I looked up a documentation about configuration of check but it seems we cannot configure to not detect particular attribute.

I'd be happy if we could have more control over check command.

More precisely, I think we could have "allowed_attributes" config option to ignore particular attribute in HTML during check.