I read through https://github.github.com/gfm/#example-199 and #145 to understand a bit better and I'm not sure what's the best course of action here: the HTML spec for td (and th just below) don't like align as a valid attribute.

For more context, I discovered this issue when working on rust-lang/rust#84480. The goal is to check that rustdoc generated pages are completely valid by using tidy. The problem is that it's an invalid attribute because not listed in the spec. The solution would be to rename align into data-align. However, the browsers are using this attribute to change the content display. So maybe the best thing to do is to simply ignore this warning and keep things as is... If so, please just close the issue.