added default document root

nginx.conf

@@ -30,6 +30,9 @@ http {
     # set default index options for all sites
     index index.html index.htm;
 
+    # set default document root for all sites
+    root /usr/share/nginx/html;
+    
     # logging options
     log_format main '$remote_addr - $remote_user [$time_local] $request '
         '$status $body_bytes_sent "$http_referer" '