Do not provide the output file as an argument

Signed-off-by: Antoine Tenart <antoine.tenart@ack.tf>

.gitignore

@@ -1 +1,2 @@
-blacklist-zone
+blacklist
+blacklist.txt

main.go

@@ -27,15 +27,10 @@ var (
 		"ip6-mcastprefix", "ip6-allnodes", "ip6-allrouters",
 		"ip6-allhosts",
 	}
+	zone_file = "blacklist.txt"
 )
 
 func main() {
-	if len(os.Args) < 2 {
-		log.Fatal("Please provide a zone file to write to.")
-	}
-
-	zone_file := os.Args[1]
-
 	// Open the zone file, and create it if needed
 	f, err := os.OpenFile(zone_file, os.O_CREATE|os.O_APPEND|os.O_WRONLY, 0644)
 	if err != nil {