Make demon gating show a message

This was both an accessibility and comprehensibility issue.

doc/fixes36.2

@@ -342,6 +342,7 @@ the simulation of dual weapon combat when polymorphed into a form with more
 	used seconary weapon even when wearing a shield, or if it was silver
 	even when current shape couldn't handle silver, or if it was cursed;
 	cursed is allowed but weapon will be dropped, just like in two-weapon
+demons gated in other demons without any message
 
 
 Fixes to Post-3.6.1 Problems that Were Exposed Via git Repository

src/minion.c

@@ -143,6 +143,8 @@ struct monst *mon;
                 EMIN(mtmp)->renegade =
                     (atyp != u.ualign.type) ^ !mtmp->mpeaceful;
             }
+            if (is_demon(ptr) && canseemon(mtmp))
+                pline("%s appears in a cloud of smoke!", Amonnam(mtmp));
         }
         cnt--;
     }