Make List documentation more consistent (#19108)

(This is tied to scala/scala#10616 and all
description/discussion is in that PR.)

Author: nicolasstucki

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

@@ -2237,7 +2237,7 @@ class Definitions {
     """.stripMargin)
 
     add(Any_hashCode,
-    """/** Calculate a hash code value for the object.
+    """/** Calculates a hash code value for the object.
       | *
       | *  The default hashing algorithm is platform dependent.
       | *