Update signature to match that of the list variant.

Closes #1604

Author: coke

doc/Type/Any.pod6

@@ -663,7 +663,7 @@ L«C<List.permutations>|/type/List#routine_permutations» on it.
 
 Defined As:
 
-    method categorize(&mapper --> Seq)
+    method categorize(&mapper --> Hash:D)
 
 Treats the C<Any> as a 1-item list and uses
 L«C<List.categorize>|/type/List#routine_categorize» on it.
@@ -674,7 +674,7 @@ L«C<List.categorize>|/type/List#routine_categorize» on it.
 
 Defined As:
 
-    method classify(&mapper --> Seq)
+    method classify(&mapper -->Hash:D)
 
 Treats the C<Any> as a 1-item list and uses
 L«C<List.classify>|/type/List#routine_classify» on it.