docs: clarify server.sourcemapIgnoreList docs (#12325)

Co-authored-by: Ben McCann <322311+benmccann@users.noreply.github.com>

docs/config/server-options.md

@@ -326,16 +326,22 @@ export default defineConfig({
 
 Whether or not to ignore source files in the server sourcemap, used to populate the [`x_google_ignoreList` source map extension](https://developer.chrome.com/blog/devtools-better-angular-debugging/#the-x_google_ignorelist-source-map-extension).
 
-`server.sourcemapIgnoreList` is the equivalent of [build.rollupOptions.output.sourcemapIgnoreList](https://rollupjs.org/configuration-options/#output-sourcemapignorelist) for the dev server. A difference between the two config options is that the rollup function is called with a relative path for `sourcePath` while `server.sourcemapIgnoreList` is called with an absolute path. During dev, most modules have the map and the source in the same folder, so the relative path for `sourcePath` is the file name itself. In these cases, absolute paths makes it convenient to be used instead.
+`server.sourcemapIgnoreList` is the equivalent of [`build.rollupOptions.output.sourcemapIgnoreList`](https://rollupjs.org/configuration-options/#output-sourcemapignorelist) for the dev server. A difference between the two config options is that the rollup function is called with a relative path for `sourcePath` while `server.sourcemapIgnoreList` is called with an absolute path. During dev, most modules have the map and the source in the same folder, so the relative path for `sourcePath` is the file name itself. In these cases, absolute paths makes it convenient to be used instead.
 
 By default, it excludes all paths containing `node_modules`. You can pass `false` to disable this behavior, or, for full control, a function that takes the source path and sourcemap path and returns whether to ignore the source path.
 
 ```js
 export default defineConfig({
   server: {
-    // This is the default value, and will add all files with node_modules in their paths
-    // to the ignore list.
-    sourcemapIgnoreList: (sourcePath, sourcemapPath) => sourcePath.includes('node_modules')
+    // This is the default value, and will add all files with node_modules
+    // in their paths to the ignore list.
+    sourcemapIgnoreList(sourcePath, sourcemapPath) {
+      return sourcePath.includes('node_modules')
+    }
   }
 };
 ```
+
+::: tip Note
+[`server.sourcemapIgnoreList`](#server-sourcemapignorelist) and [`build.rollupOptions.output.sourcemapIgnoreList`](https://rollupjs.org/configuration-options/#output-sourcemapignorelist) need to be set independently. `server.sourcemapIgnoreList` is a server only config and doesn't get its default value from the defined rollup options.
+:::