Move root out of location context

We are also loading images, (like favicon.ico), these will also redirect to index.php.
Side effect, this causes the CSRF to be regenerated in the session.

docker/nginx/nginx.conf

@@ -29,12 +29,12 @@ http {
         listen [::]:80 default_server;
         server_name _;
 
+        root /var/www/html;
         location / {
             try_files $uri $uri/ /index.php$is_args$args;
         }
 
         location ~ \.php$ {
-            root /var/www/html;
             fastcgi_split_path_info ^(.+\.php)(/.+)$;
             fastcgi_pass php-fpm:9000;
             fastcgi_index index.php;
@@ -46,4 +46,4 @@ http {
             gzip off;
         }
     }
-}
+}