fix link

Author: lobsterkatie

src/includes/configuration/sourcemaps/tools/webpack/advanced-usage/javascript.nextjs.mdx

@@ -23,4 +23,4 @@ const SentryWebpackPluginOptions = {
 module.exports = withSentryConfig(moduleExports, SentryWebpackPluginOptions);
 ```
 
-Learn more about the Webpack usage for the Next.js SDK in [Extend Default Webpack Usage](/platforms/javascript/guides/nextjs/manual-setup/#extend-default-webpack-usage).
+Learn more about the Webpack usage for the Next.js SDK in [Extend Default Webpack Usage](/platforms/javascript/guides/nextjs/manual-setup/#extend-nextjs-configuration).