Update asset_mapper.rst

Author: ThomasLandauer

frontend/asset_mapper.rst

@@ -1084,7 +1084,7 @@ have *one* importmap, so ``importmap()`` must be called exactly once.
 If you want to execute *only* ``checkout.js``
 and *not* ``app.js``, pass only ``checkout`` to ``importmap()``.
 In this case, still **both** files are added to ``<script type="importmap">``,
-but only ``checkout.js`` is executed (via ``<link rel="modulepreload">``).
+but only ``checkout`` is executed (via ``<script type="module">import 'checkout';</script>``).
 
 Using a Content Security Policy (CSP)
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