I have a K66F freedom board and loaded MCUXpresso. In demo: "frdmk66f_demo_apps_lwip_lwip_httpsrv_bm" the directory "FS" and the "Index" page and the "404.html" paths have a slash through them and cannot be changed. I want to put another webpage in this location. How do I unlock or add my own web page to this? I have never seen a slash through the directory. I can change the Index file, it builds ok, just no changes show up when I pull up the web page.