docs: update $fetch documentation (#19356)

Co-authored-by: Özüm Eldoğan <ozum@users.noreply.github.com>
Co-authored-by: Sébastien Chopin <seb@nuxtlabs.com>
Co-authored-by: Sébastien Chopin <seb@nuxt.com>

docs/3.api/3.utils/$fetch.md

@@ -7,12 +7,42 @@ description: Nuxt uses ofetch to expose globally the $fetch helper for making HT
 
 Nuxt uses [ofetch](https://github.com/unjs/ofetch) to expose globally the `$fetch` helper for making HTTP requests within your Vue app or API routes.
 
-::ReadMore{link="/docs/getting-started/data-fetching"}
-::
-
 During server-side rendering, calling `$fetch` to fetch your internal [API routes](/docs/guide/directory-structure/server) will directly call the relevant function (emulating the request), **saving an additional API call**.
 
-Note that `$fetch` is the preferred way to make HTTP calls in Nuxt 3 instead of [@nuxt/http](https://github.com/nuxt/http) and [@nuxtjs/axios](https://github.com/nuxt-community/axios-module) that are made for Nuxt 2.
+However, using `$fetch` in components without wrapping it with `useAsyncData` causes fetching the data twice: initially on the server, then again on the client-side during hydration, because `$fetch` does not transfer state from the server to the client. Thus, the fetch will be executed on both sides because the client has to get the data again.
 
-::NeedContribution
+We recommend to use [`useFetch`](https://nuxt.com/docs/api/composables/use-fetch) or [`useAsyncData`](https://nuxt.com/docs/api/composables/use-async-data) + `$fetch` to prevent double data fetching when fetching the component data.
-::
+
+```vue
+<script setup>
+// During SSR data is fetched twice, one on the server and one on the client.
+const dataTwice = await $fetch("/api/item")
+
+// During SSR data is fetched only on the server side and transferred to the client.
+const { data } = await useAsyncData('item', () => $fetch('/api/item'))
+
+// You can also useFetch as shortcut of useAsyncData + $fetch
+const { data } = await useFetch('/api/item')
+</script>
+```
+
+:ReadMore{link="/docs/getting-started/data-fetching"}
+
+You can use `$fetch` for any method that are executed only on client-side.
+
+```vue
+<script setup>
+function contactForm() {
+  $fetch('/api/contact', {
+    method: 'POST',
+    body: { hello: 'world '}
+  })
+}
+</script>
+
+<template>
+  <button @click="contactForm">Contact</button>
+</template>
+```
+
+`$fetch` is the preferred way to make HTTP calls in Nuxt instead of [@nuxt/http](https://github.com/nuxt/http) and [@nuxtjs/axios](https://github.com/nuxt-community/axios-module) that are made for Nuxt 2.