[css-logical] border radii not shorthands

The Flow-relative Border Radius properties are longhands, not
shorthands.

resolves #3035

Author: ericwilligers

css-logical-1/Overview.bs

@@ -645,7 +645,7 @@ the 'border-block-start', 'border-block-end', 'border-inline-start', 'border-inl
   'border-inline-start' & 'border-inline-end',
   respectively.
 
-<h3 id="border-radius-shorthands">
+<h3 id="border-radius-properties">
 Flow-relative Corner Rounding:
 the 'border-start-start-radius', 'border-start-end-radius', 'border-end-start-radius', 'border-end-end-radius' properties</h3>