fix: remove fallback

Author: fi3ework

src/content/configuration/externals.mdx

@@ -574,13 +574,23 @@ async function foo() {
 
 Note that there will be an `import` or `import()` statement in the output bundle.
 
-When a module is not imported via `import` or `import()`, webpack will determine which type of external to use as fallback based on the configuration of [`externalsPresets`](#externalspresets). When one of the previous `externalsPresets` type is enabled, the following `externalsPresets` type will no longer apply. The order is listed below.
+When a module is not imported via `import` or `import()`, webpack will use `"module"` externals type as fallback. If you want to use a different type of externals as fallback, you can specify it with a function in the `externals` option. For example:
 
-- When `externalsPresets.web` is `true`, use `module`.
-- When `externalsPresets.webAsync` is `true`, use `import`.
-- When node.js related (`electron`, `electronMain`, `electronPreload`, `electronRenderer`, `node`, `nwjs`) externalsPresets is true, use `node-commonjs`.
-
-When none of the above `externalsPresets` type is enabled or can be derived, webpack will use `commonjs` as the default type.
+```js
+module.exports = {
+  externalsType: "module-import",
+  externals: [
+    function (
+      { request, dependencyType },
+      callback
+    ) {
+      if (dependencyType === "commonjs") {
+        return callback(null, `node-commonjs ${request}`);
+      }
+      callback();
+    },
+  ]
+```
 
 ### externalsType.node-commonjs