Update installation.md

Docs: Added hint for the correct order of custom code when using Alpine as a module

packages/docs/src/en/essentials/installation.md

@@ -60,3 +60,9 @@ Alpine.start()
 ```
 
 > The `window.Alpine = Alpine` bit is optional, but is nice to have for freedom and flexibility. Like when tinkering with Alpine from the devtools for example.
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+> If you imported Alpine into a bundle, you have to make sure you are registering any extension code IN BETWEEN when you import the `Alpine` global object, and when you initialize Alpine by calling `Alpine.start()`. 
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+[→ Read more about extending Alpine](/advanced/extending)