Update doc

Author: mbovel

compiler/src/dotty/tools/dotc/core/Types.scala

@@ -1403,9 +1403,9 @@ object Types extends TypeUtils {
       case tp =>
         tp
 
-    /** Widen all top-level singletons reachable by dealiasing
-     *  and going to the operands of & and |.
-     *  Overridden and cached in OrType.
+    /** Widen all top-level singletons reachable by dealiasing and going to the
+     *  operands of intersections and soft unions (only when `skipSoftUnions` is
+     *  `false`). Overridden and cached in [[OrType]].
      */
     def widenSingletons(skipSoftUnions: Boolean = false)(using Context): Type = dealias match {
       case tp: SingletonType =>