add dedicated user for better permission control

build/config/nginx.conf

@@ -2,7 +2,7 @@
 ### NGINX main configuration
 #
 
-user nginx;
+user www-docker;
 worker_processes 1;
 pid /var/run/nginx.pid;
 
@@ -24,7 +24,7 @@ http {
     include /etc/nginx/mime.types;
 
     # set default index and webroot
-    index index.php index.html;
+    index index.html index.htm default.htm;
     root /usr/share/nginx/html;
 
     # logging options (off by default for performance)