Add some missing relative units

[floh1695]

Simply adds some relative units I noticed were missing

[turion]

I couldn't find documentation for these, can you point me to it?

[ddssff]

I see a number of them here: https://drafts.csswg.org/css-values-4/#cap

[floh1695]

I originally found these all listed here https://developer.mozilla.org/en-US/docs/Learn/CSS/Building_blocks/Values_and_units#lengths

From the spec @ddssff posted, ch, lh, rlh, vb, and vi are listed at https://drafts.csswg.org/css-values-4/#relative-lengths with svw, svh, lvw, lvh, dvw, and dvh being listed at https://drafts.csswg.org/css-values-4/#viewport-relative-units

[turion]

Thanks for the clarifications!