Inserted sample nginx config for API in api_nginx-frontend.conf (#4382)

Co-authored-by: Sven Reichel <github-sr@hotmail.com>

Author: kiatng

dev/openmage/nginx-frontend.conf

@@ -153,6 +153,15 @@ server {
     location /api/ { return 404; }
     location /api.php { return 404; }
 
+    # Clients use the frontend to call API
+    #location /api {
+    #    root $webroot;
+    #    rewrite ^/api/(\w+).*$ /api.php?type=$1 last;
+    #    set $fastcgi_script_filename $webroot/api.php;
+    #    set $fastcgi_script_name2 /api.php;
+    #    try_files NOT_EXISTS @php-fpm;
+    #}
+
     # Protect dot files no matter where they are located
     location ~ /\. { return 404; }