[css-writing-modes-3] Writing-modes spec has broken link to css-sizing-3

[dholbert]

https://drafts.csswg.org/css-writing-modes-3/#orthogonal-auto

Section "7.3.1. Available Space of Orthogonal Flows" ends with this text:

See [[!css-sizing-3]] for further details on CSS sizing terminology and concepts.

Screenshot:

I suspect that's meant to be a real link, populated by bikeshed preprocessing, but that's failing due to some sort of typo?

[tabatkins]

Yup, there was an unclosed dfn that now prevents certain things from parsing. Fixed, and cleaned up the bikeshed errors generally.