docs: add examples for useLazyFetch and useLazyAsyncData (#3418)

docs/content/3.docs/1.usage/1.data-fetching.md

@@ -71,6 +71,24 @@ const { data } = await useAsyncData('count', () => $fetch('/api/count'))
 
 This composable behaves identically to `useAsyncData` with the `lazy: true` option set. In other words, the async function does not block navigation. That means you will need to handle the situation where the data is `null` (or whatever value you have provided in a custom `default` factory function).
 
+### Example
+
+```vue
+<template>
+  <div>
+    {{ pending ? 'Loading' : count }}
+  </div>
+</template>
+
+<script setup>
+const { pending, data: count } = useLazyAsyncData('count', () => $fetch('/api/count'))
+watch(count, (newCount) => {
+  // Because count starts out null, you won't have access
+  // to its contents immediately, but you can watch it.
+})
+</script>
+```
+
 ## `useFetch`
 
 Within your pages, components and plugins you can use `useFetch` to universally fetch from any URL.
@@ -121,6 +139,30 @@ const { data } = await useFetch('/api/count')
 
 This composable behaves identically to `useFetch` with the `lazy: true` option set. In other words, the async function does not block navigation. That means you will need to handle the situation where the data is `null` (or whatever value you have provided in a custom `default` factory function).
 
+### Example
+
+```vue
+<template>
+  <!-- you'll need to handle a loading state -->
+  <div v-if="pending">
+    Loading ...
+  </div>
+  <div v-else>
+    <div v-for="post in posts">
+      <!-- do something -->
+    </div>
+  </div>
+</template>
+
+<script setup>
+const { pending, data: posts } = useLazyFetch('/api/posts')
+watch(posts, (newPosts) => {
+  // Because posts starts out null, you won't have access
+  // to its contents immediately, but you can watch it.
+})
+</script>
+```
+
 ## Isomorphic fetch
 
 When we call `fetch` in the browser, user headers like `cookie` will be directly sent to the API.