[css-multicol] editorial: <line-width> tooltip is incomplete

[MatsPalmgren]

https://drafts.csswg.org/css-multicol/#crw
Hover the <line-width> link - a tooltip appears that says "Expands to: medium | thick | thin".
This is misleading since it omits <length [0,∞]> (which you will see if you click the link).

This might be an issue that affects other specs too...

CC @tabatkins

[tabatkins]

Yeah it probably does affect a bunch. Terminals are expanded like that from dfns listed as for="<that-terminal>"; following the <line-width> length, I see that only the keywords are actually dfn'd for it.

Since Reffy is collecting grammars, I can probably switch this feature over to using that data; it'll presumably be more complete. I should investigate this.