Revert "Don't recommend code that does not work"

This reverts commit 7008429.

Author: AlexDaniel

doc/Type/Proc/Async.pod6

@@ -14,10 +14,6 @@ moment.
 C<Proc::Async> allows you to run external commands asynchronously, capturing
 standard output and error handles, and optionally write to its standard input.
 
-=begin comment
-⚠ Revert the commit mentioned in RT #132016 once it is resolved
-=end comment
-
     my $file = ‘foo’.IO;
     spurt $file, “and\nCamelia\n♡\nme\n”;
 
@@ -38,11 +34,11 @@ standard output and error handles, and optionally write to its standard input.
         whenever $proc.print: “I\n♥\nCamelia\n” {
             $proc.close-stdin
         }
-        whenever signal(SIGTERM) {
+        whenever signal(SIGTERM).merge: signal(SIGINT) {
             once {
                 say ‘Signal received, asking the process to stop’;
                 $proc.kill; # sends SIGHUP, change appropriately
-                whenever signal($_) {
+                whenever signal($_).zip: Promise.in(2).Supply {
                     say ‘Kill it!’;
                     $proc.kill: SIGKILL
                 }