Spec: document attribute filtering on github.com #220
Description
(This is more of a https://github.github.com/gfm/ issue, but I really can't find a separate repo for it. Where on Earth is its repo?)
The GitHub renderer on GitHub.com seems to also filter HTML attributes, but that behavior is not reflected in the spec, and a quick look does not reveal such functionality in cmark-gfm either. It will make stuff a lot more user-friendly if GitHub can document the allowed attributes, especially since people will want to use some fancy layouts on their personal README.
For example, the following does not work for now, even though a read of the spec suggests it would be allowed:
<div style="background: while; column-width: 15em">
* 1
* 2
* 3
</div>- 1
- 2
- 3
Similarly, table border=0 doesn't seem to work.