[css-values-4] Calc notation - Exercise 28 - typo

[mateitudor]

There's a typo right after Example 28: 'altho' → 'although'
https://drafts.csswg.org/css-values-4/#calc-func

[Loirooriol]

#5850 (comment) resolved to treat this as a typo indeed.

[fantasai]

Fixed, thanks for reporting. :)