adds Defined as section, close #2900

doc/Type/List.pod6

@@ -267,8 +267,14 @@ will also return a C<Junction> with concatenation done as much as possible:
 
 =head2 routine map
 
-This method or sub is defined in L<C<Any>|/type/Any#method_map>. Examples
-applied to lists are included here for the purpose of illustration.
+Defined as:
+    multi method map(Hash:D \hash)
+    multi method map(Iterable:D \iterable)
+    multi method map(|c)
+    multi method map(\SELF: &block;; :$label, :$item)
+    multi sub map(&code, +values)
+
+Examples applied to lists are included here for the purpose of illustration.
 
 For a list, it invokes C<&code> for each element and gathers the return values
 in a sequence and returns it. This happens lazily, i.e. C<&code> is only invoked