add example certificate and key files generated with acme-client.

ok florian

src/etc/examples/httpd.conf

@@ -1,4 +1,4 @@
-# $OpenBSD: httpd.conf,v 1.14 2015/02/04 08:39:35 florian Exp $
+# $OpenBSD: httpd.conf,v 1.15 2016/09/17 15:04:15 tj Exp $
 
 #
 # Macros
@@ -49,6 +49,10 @@ server "www.example.com" {
 server "secure.example.com" {
 	listen on 127.0.0.1 tls port 443
 
+	# TLS certificate and key files created with acme-client(1)             
+	tls certificate /etc/ssl/acme/fullchain.pem                             
+	tls key /etc/ssl/acme/private/privkey.pem
+
 	# Define server-specific log files relative to /logs
 	log { access "secure-access.log", error "secure-error.log" }