Elaborate a bit about ===

- show that it disregards containers
- put in link to ValueObjAt to create custom .WHICH methods

doc/Language/operators.pod6

@@ -1762,7 +1762,8 @@ implement an appropriate infix C<eqv> operator:
 
     sub infix:<===>(Any, Any)
 
-X<Value identity operator>. Returns C<True> if both arguments are the same object.
+X<Value identity operator>. Returns C<True> if both arguments are the same
+object, disregarding any containerization.
 
     my class A { };
     my $a = A.new;
@@ -1775,11 +1776,18 @@ For value types, C<===> behaves like C<eqv>:
     say 'a' === 'a';            # OUTPUT: «True␤»
     say 'a' === 'b';            # OUTPUT: «False␤»
 
+    my $b = 'a';
+    say $b === 'a';             # OUTPUT: «True␤»
+
     # different types
     say 1 === 1.0;              # OUTPUT: «False␤»
 
-C<===> uses the L<WHICH|/routine/WHICH> method to obtain the object identity, so all value
-types must override method C<WHICH>.
+C<===> uses the L<WHICH|/routine/WHICH> method to obtain the object identity.
+
+If you want to create a class that should act as a value type, then that
+class must create an instance method C<WHICH>, that should return a
+L<CValueObjAt|type/ValueObjAt> object that won't change for the lifetime of
+the object.
 
 =head2 infix C«=:=»