vnode.attrs.tags behavior isn't documented, leads to bad places

[thequailman]

Is there an existing issue for this?

• I have searched the existing issues

Offending URL

https://mithril.js.org/hyperscript.html

Issue description

I have been using Mithril for years and just ran into the issue with passing tag as a component attribute as described here MithrilJS/mithril.js#2478. I can't believe this isn't documented somewhere, I spent at least 2 hours debugging why my component was receiving empty vnode.attrs. I'm opening this as documentation issue, but I think this is a footgun waiting to happen.