nginx: make user in nginx.conf consistent with the default value

It gets replaces with the real NGINX_USER anyway, but it confuses people
that there is a different value by default. So just make it the same as the
default NGINX_USER

Signed-off-by: Pascal Bach <pascal.bach@siemens.com>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>

meta-webserver/recipes-httpd/nginx/files/nginx.conf

@@ -1,5 +1,5 @@
 
-user  www-data;
+user  www;
 worker_processes  1;
 
 error_log  /var/log/nginx/error.log;