Show how to go from signal numbers to Signal objects to use with the signal method

Author: samcv

doc/Type/Supply.pod6

@@ -601,6 +601,9 @@ the supply.  For example:
 
 would catch Control-C, thank you, and then exit.  The list of supported
 signals can be found by checking Signal::.keys (as you would any enum).
+To go from a signal number to Signal, you can do something like this:
+
+    signal(Signal(2)).tap( -> $sig { say "Received signal: $sig" } );
 
 =head2 method IO::Notification.watch-path