Replace ash shell with dash in contrib/reverse-dns.
diff --git a/contrib/reverse-dns/README b/contrib/reverse-dns/README
index 9fd4efb..db9ca77 100644
--- a/contrib/reverse-dns/README
+++ b/contrib/reverse-dns/README
@@ -14,5 +14,5 @@
 

 in the dnsmasq configuration.

 

-The script runs on debian (with ash installed) and on busybox.

+The script runs on debian (with dash installed) and on busybox.