Minor documentation fix on BorderRadiusDirectional.zero (#117661)

Author: gnprice

packages/flutter/lib/src/painting/border_radius.dart

@@ -590,7 +590,7 @@ class BorderRadiusDirectional extends BorderRadiusGeometry {
 
   /// A border radius with all zero radii.
   ///
-  /// Consider using [EdgeInsets.zero] instead, since that object has the same
+  /// Consider using [BorderRadius.zero] instead, since that object has the same
   /// effect, but will be cheaper to [resolve].
   static const BorderRadiusDirectional zero = BorderRadiusDirectional.all(Radius.zero);