docs: get event before running async function (#8861)

docs/content/1.getting-started/6.data-fetching.md

@@ -238,9 +238,8 @@ The example below adds the request headers to an isomorphic `$fetch` call to ens
 
 ```vue
 <script setup>
-const { data } = await useFetch('/api/me', {
-  headers: useRequestHeaders(['cookie'])
-})
+const headers = useRequestHeaders(['cookie'])
+const { data } = await useFetch('/api/me', { headers })
 </script>
 ```
 
@@ -262,11 +261,11 @@ Here is a list of common headers that are NOT to be proxied:
  If you want to pass on/proxy cookies in the other direction, from an internal request back to the client, you will need to handle this yourself.
 
 ```ts [composables/fetch.ts]
-export const fetchWithCookie = async (url: string) => {
+export const fetchWithCookie = async (event: H3Event, url: string) => {
   const res = await $fetch.raw(url)
   const cookies = (res.headers.get('set-cookie') || '').split(',')
   for (const cookie of cookies) {
-    appendHeader(useRequestEvent(), 'set-cookie', cookie)
+    appendHeader(event, 'set-cookie', cookie)
   }
   return res._data
 }
@@ -275,7 +274,8 @@ export const fetchWithCookie = async (url: string) => {
 ```vue
 <script setup lang="ts">
 // This composable will automatically pass cookies to the client
-const result = await fetchWithCookie('/api/with-cookie')
+const event = useRequestEvent()
+const result = await fetchWithCookie(event, '/api/with-cookie')
 onMounted(() => console.log(document.cookie))
 </script>
 ```