Server backed saving routes

README.md

@@ -8,10 +8,10 @@ A small static webpage for saving and sharing Google Maps route links.
 - Optional date, description, and uploaded picture
 - Click route names to open saved Google Maps links
 - Edit, remove, share, or copy route links
-- Data is stored locally in the browser with `localStorage`
+- Routes are stored on the webserver in `data/routes.json`
 - Simple secret gate before the app opens
 
-Open `index.html` in a browser to use it.
+Deploy the files to a PHP-enabled webserver and open `index.html` in a browser.
 
 ## Secret
 
@@ -25,4 +25,6 @@ cp config.example.js config.js
 window.ROUTES_SECRET = "your-secret";
 ```
 
-`config.js` is gitignored. This is a simple client-side gate, not strong server-side security.
+`config.js` is gitignored. `api.php` reads the same secret and stores shared routes in `data/routes.json`, which is also gitignored.
+
+Make sure the webserver user can write to the `data/` directory. This is a simple shared-secret gate, not strong security.