Fixed a textual mistake.

yard/scripts/make_debian

@@ -591,7 +591,7 @@ sub start_up {
     if ($dpkg_result != 0) {
 	die "Swim is required:\n\n" .
             "Add one of these lines to your /etc/apt/sources.list:\n" .
-	    "deb http://prdownloads.sourceforge.net/avd ./  orx\n" .
+	    "deb http://prdownloads.sourceforge.net/avd ./  or\n" .
 	    "deb http://download.sourceforge.net/avd ./\n\n" .
             "Then do `apt-get update` and `apt-get install swim`\n" .
             "";
@@ -606,7 +606,7 @@ sub start_up {
 		if (/purge|deinstall/) {
 		    die "Swim needs to be reinstalled:\n\n" .
 	       "Add one of these lines to your /etc/apt/sources.list:\n" .
-	       "deb http://prdownloads.sourceforge.net/avd ./  orx\n" .
+	       "deb http://prdownloads.sourceforge.net/avd ./  or\n" .
 	       "deb http://download.sourceforge.net/avd ./\n\n" .
 	       "Then do `apt-get update` and `apt-get install swim`\n" .
             "";