[css-align] note about what CSSOM requires should link to the section

[dbaron]

The section on baseline alignment values says:

Note: Because they are equivalent, and baseline is shorter, the CSSOM serializes first baseline as baseline.

This should link to the definition in question. (I'm curious where it is, or if it exists!)

[fantasai]

The definition was here, in AnneVK's draft:
https://www.w3.org/TR/2011/WD-cssom-20110712/#serializing-css-values
But it seems to have disappeared in the next revision by Glenn and zcorpan:
https://www.w3.org/TR/2013/WD-cssom-20131205/#serializing-css-values
We've filed an issue on this regression: #1564
We'll update with a link once that's fixed.