docs: fix wrong code in entry-context.mdx (#1897)

Author: lio-mengxiang

src/content/configuration/entry-context.mdx

@@ -101,8 +101,8 @@ module.exports = {
   //...
   entry: {
     app: './app.js',
-    home: { import: './contact.js', filename: 'pages/[name][ext]' },
-    about: { import: './about.js', filename: 'pages/[name][ext]' },
+    home: { import: './contact.js', filename: 'pages/[name].js' },
+    about: { import: './about.js', filename: 'pages/[name].js' },
   },
 };
 ```