update README

README.md

 # DUP Tools front
 
-Based on the [create-wasm-app] template to provide a full js interface using `dup-tools-wasm`, a toolbox for developers wishing to use the DUP procotole.
+Based on the [create-wasm-app] template to provide a full js interface using [dup-tools-wasm], a toolbox for developers wishing to use the DUP procotole.
 
 Currently, only the document validator feature is implemented, but the `dup-tools-wasm` library already allows you to do potentially much more !
 
 [create-wasm-app]: https://github.com/rustwasm/create-wasm-app.git
+[dup-tools-wasm]: https://git.duniter.org/tools/dup-tools-wasm
+
+## Supported browsers
+
+* Firefox
+* Chrome/Chromium
 
 ## Usage
 
+You can use DUP Tools directly on the web:  [https://tools.duniter.io/dup-tools-front/](https://tools.duniter.io/dup-tools-front/).
+
 For local use, you only need `npm` :
 
 ```
@@ -17,7 +25,10 @@ npm start
 
 Then open `localhost:8080` in a supported browser.
 
-## Supported browsers
+### Change port
 
-* Firefox
-* Chrome/Chromium
+If you are already using port `8080` for your development, you can change the port by modifying `package.json` file as follows :
+
+In the `scripts` section, modify the `start` command:
+
+Replace `"start": "webpack-dev-server"` by `"start": "webpack-dev-server --port NEW_PORT"`