Fixed incorrectly defined return value

Author: Jan-Olof Hendig

doc/Type/Cool.pod6

@@ -1070,7 +1070,7 @@ L<Regex|/type/Regex> as a list of strings.
 
 =head2 method contains
 
-    multi method contains(Cool:D: Str(Cool) $needle, Cool $start?) returns True:D
+    multi method contains(Cool:D: Str(Cool) $needle, Cool $start?) returns Bool:D
 
 Returns C<True> if the invocant contains the C<$needle> at any position within
 the string. If $start is provided skip as many characters.