fix a link to a type;

Author: coke

doc/Language/signatures.rakudoc

@@ -1118,7 +1118,7 @@ operator C<|>.
     c(42, "answer");
     # OUTPUT: «Capture␤Int Str␤»
 
-One can also constrain the arguments subject to a C<Capture> by using a sub-signature.
+One can also constrain the arguments subject to a L<C<Capture>|/type/Capture> by using a sub-signature.
 
     sub d(|cap(Int, Str, *%)) { put "called with {cap.raku}" };
     d(41);