Add documentation for server:watch script (#336)

The new script was introduced in MagicMirrorOrg/MagicMirror#3920.

Author: KristjanESPERANTO

configuration/introduction.md

@@ -59,6 +59,7 @@ The following properties can be configured, place them above the modules item:
 | `electronOptions`  | An optional array of Electron (browser) options. This allows configuration of e.g. the browser screen size and position (example: `electronOptions: { fullscreen: false, width: 800, height: 600 }`). Kiosk mode can be enabled by setting `kiosk: true`, `autoHideMenuBar: false` and `fullscreen: false`. More options can be found [here](https://github.com/electron/electron/blob/master/docs/api/browser-window.md). This will most likely be used in advanced installations, below.                                                                | []                                         |
 | `electronSwitches` | An optional array of Electron switches. This allows configuration of electron app itself. <br> This properties will not affect the `serveronly` mode. Usually normal `MM` users don't need this property, but if you are a hard-core hacker, you might need this to handle Electron itself over `MagicMirror` provides. More options can be found [here](https://www.electronjs.org/docs/latest/api/command-line-switches) (Not all available switches are described there.)<br>example:`electronSwitches:["enable-transparent-visuals", "disable-gpu"];` | []                                         |
 | `customCss`        | The path of the `custom.css` stylesheet. The default is `css/custom.css`.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 | `css/custom.css`                           |
+| `watchTargets`     | An optional array of file paths to monitor when using `node --run server:watch`. When any of these files change, the server automatically restarts and connected browsers reload. Particularly useful when frequently modifying `config.js`, `custom.css`, or module files during development or setup. Example: `watchTargets: ["config/config.js", "css/custom.css", "modules/MMM-MyModule/MMM-MyModule.js"]`. See [Development Mode](/core-development/debugging.html#development-mode-with-auto-reload) for more details.                     | `undefined`                                |
 
 After the above options, you will then add modules. See
 [module configuration](/modules/configuration.md) for more information.

core-development/debugging.md

@@ -30,18 +30,50 @@ Developer consoles in browsers and the Electron app (typically CTRL+SHIFT+I to
 toggle open/close) can be used to set client-side breakpoints, step through
 scripts and inspect variables.
 
+## Watch Mode with Auto-Reload
+
+For active development, MagicMirror² provides a `server:watch` script that automatically restarts the server and reloads connected browsers when files change:
+
+```sh
+node --run server:watch
+```
+
+This mode monitors files specified in your `config.js` under the `watchTargets` property:
+
+```js
+let config = {
+  watchTargets: [
+    "config/config.js",
+    "css/custom.css",
+    "modules/MMM-MyModule/MMM-MyModule.js",
+    "modules/MMM-MyModule/node_helper.js"
+  ],
+  // ... rest of config
+};
+```
+
+When any monitored file changes:
+1. The server automatically restarts
+2. Waits for the port to become available
+3. Sends a reload notification to all connected browsers via Socket.io
+4. Browsers automatically refresh to show the changes
+
+This creates a seamless development experience where you can edit code, save, and see the results within seconds without manual restarts.
+
+**Note:** If `watchTargets` is empty or undefined, the watcher starts but monitors nothing.
+
 ## Logging
 
 While there are no log files produced by the server, info is reported in two
 different places:
 
-- The console when running from `npm run start` or `npm run server`.
+- The console when running from `node --run start`, `node --run server`, or `node --run server:watch`.
   - This is separated into two streams, `console.log()` is output as the
     `stdout` stream, and
   - `console.error()` is output as the `stderr` stream.
   - These can be redirected to files when starting the server. `>` will redirect
     `stdout`, and `2>` will redirect `stderr`. `2>&1` will combine both streams:
-    `npm run start > out.log 2>&1`
+    `node --run start > out.log 2>&1`
 - The browser's developer console (typically CTRL+SHIFT+I to toggle open/close)
   will have output from scripts that run on the browser.
 
@@ -113,5 +145,5 @@ script, such as `start:dev`:
 Or when running from the command line (Linux example):
 
 ```sh
-TZ=Europe/Madrid npm run start:dev
+TZ=Europe/Madrid node --run start:dev
 ```