recommend Proc::Async instead of Proc

Author: coke

doc/Type/IO/Pipe.pod6

@@ -11,7 +11,7 @@ it consumes string or binary data, and another where it reproduces the same
 data. It is buffered, so that a write without a read doesn't immediately
 block.
 
-Pipes can be easily constructed with L<sub run and Proc.new|/type/Proc>.
+Pipes can be easily constructed with L<sub run and Proc::Async.new|/type/Proc:Async>.
 
 =head1 Methods