[css-text-decor] text-decoration-thickness property still refered to by `text-decoration-width-property` anchor

[drott]

The property text-decoration-thickness property after its rename is still referred to by the #text-decoration-width-property anchor, e.g. in the following link: https://drafts.csswg.org/css-text-decor-4/#text-decoration-width-property

I suggest to rename the anchor as well.

[drott]

Thanks for the fix.