Add documentation for leading-[tight/snug/normal/relaxed/loose]

[joezappie]

The tailwind v4 docs doesn't mention the named variants for setting line heights:

leading-tight | line-height: 1.25;
leading-snug | line-height: 1.375;
leading-normal | line-height: 1.5;
leading-relaxed | line-height: 1.625;
leading-loose | line-height: 2;

leading-none is in the v4 docs, but the other variants still seem to work. Are they not included because they are deprecated or should they be added?

Also - is it possible with v4 to define our own named variants in the @theme {} for this? Such as having like a leading-heading or is it recommend to just make a custom utility like @utility leading-heading { line-height: 1.55em }

[joezappie]

Also I ask if its deprecated as its not in the migration guide as a deprecated utility:
https://tailwindcss.com/docs/upgrade-guide#removed-deprecated-utilities

Having line-height utilities based on font size to me seems more useful than having line height based on spacing like leading-6 when loading content from a CMS where font sizes might change. Anytime I use leading-* its with a custom value now like leading-[1.55].