docs: warn about modules with side-effects (#19592)

docs/2.guide/1.concepts/3.rendering.md

@@ -57,6 +57,10 @@ Universal rendering allows a Nuxt application to provide quick page load times w
 For more examples about writing Vue code without hydration mismatch, see [the Vue docs](https://vuejs.org/guide/scaling-up/ssr.html#hydration-mismatch).
 ::
 
+::alert{type=warning}
+When importing a library that relies on browser APIs and has side effects, make sure the component importing it is only called client-side. Bundlers do not treeshake imports of modules containing side effects.
+::
+
 ### Examples
 
 Universal rendering is very versatile and can fit almost any use case, and is especially appropriate for any content-oriented websites: **blogs, marketing websites, portfolios, e-commerce sites, and marketplaces.**