[css-conditional-4] Incorrect link pointed by `selector()`

[yarusome]

The Additions since Level 3 section has the selector() link pointing to https://drafts.csswg.org/scroll-animations-1/#valdef-scroll-timeline-source-selector, which is incorrect and misleading. The Editor's Draft version doesn't have this link, though.

Spec link: https://www.w3.org/TR/css-conditional-4/

[yarusome]

Incidentally, the section name is "Additions since Level 3" but the section id is changes-from-L4.

[estelle]

Was just about to file this same issue.

• The link from the text selector() in the abstract points to points to scroll animation

• The link from the text selector() in the changes section (see https://www.w3.org/TR/css-conditional-4/#changes-from-L4) - points to scroll animation.

• The selector() function is listed in terms defined by reference. It should instead be listed in Terms defined by this specification

These three links should likely point to https://www.w3.org/TR/css-conditional-4/#at-supports-ext or https://www.w3.org/TR/css-conditional-4/#typedef-supports-selector-fn

[svgeesus]

Most of these had now been fixed; I added the link to #typedef-supports-selector-fn.