Advertise the existence of redis-check dump --fix when logging an error about corrupted AOF file

src/aof.c

@@ -307,7 +307,7 @@ readerr:
     }
     exit(1);
 fmterr:
-    redisLog(REDIS_WARNING,"Bad file format reading the append only file");
+    redisLog(REDIS_WARNING,"Bad file format reading the append only file: make a backup of your AOF file, then use ./redis-check-dump --fix <filename>");
     exit(1);
 }