Add a note for $proc.kill

SIGHUP is likely not what most people want. Or maybe it is…
See this discussion: https://irclog.perlgeek.de/perl6/2017-09-02#i_15104886

Author: AlexDaniel

doc/Type/Proc/Async.pod6

@@ -41,7 +41,7 @@ standard output and error handles, and optionally write to its standard input.
         whenever signal(SIGTERM) {
             once {
                 say ‘Signal received, asking the process to stop’;
-                $proc.kill; # send SIGHUP
+                $proc.kill; # sends SIGHUP, change appropriately
                 whenever signal($_) {
                     say ‘Kill it!’;
                     $proc.kill: SIGKILL
@@ -50,7 +50,7 @@ standard output and error handles, and optionally write to its standard input.
         }
         whenever Promise.in(10) {
             say ‘Timeout. Asking the process to stop’;
-            $proc.kill; # send SIGHUP
+            $proc.kill; # sends SIGHUP, change appropriately
             whenever Promise.in(2) {
                 say ‘Timeout. Forcing the process to stop’;
                 $proc.kill: SIGKILL