Mention default *%_ in methods in Signature docs as well

Author: moritz

doc/Type/Signature.pod6

@@ -724,6 +724,9 @@ L<traits and modifiers|#Parameter_Traits_and_Modifiers>,
 as described in
 L<the section on slurpy array parameters|/type/Signature#Types_of_slurpy_array_parameters>.
 
+Methods automatically get a C<*%_> slurpy named parameter added if they
+don't have another slurpy named parameter declared.
+
 =head2 Types of slurpy array parameters
 
 There are three variations to slurpy array parameters.