Fix return type of comb; sjn++

Author: Altai-man

doc/Type/Cool.pod6

@@ -1150,8 +1150,8 @@ Only whitespace counts as word boundaries
 
 Defined as:
 
-    multi sub comb(Regex $matcher, Str(Cool) $input, $limit = * --> List:D)
-    multi method comb(Regex $matcher, $limit = * --> List:D)
+    multi sub comb(Regex $matcher, Str(Cool) $input, $limit = * --> Seq)
+    multi method comb(Regex $matcher, $limit = * --> Seq)
 
 Returns all (or if supplied, at most C<$limit>) matches of the invocant
 (method form) or the second argument (sub form) against the