Simplify load method, fix syntax highlighting (#5844)

* Simplify load method, fix syntax highlighting

SvelteKit now automatically infers the type of an exported load method, so no need to manually define it.

Also, Github has an ongoing issue with the Svelte syntax highlighting so using `html` is a good fallback.

* Change back to using svelte for code blocks

---------

Co-authored-by: Lachlan Collins <1667261+lachlancollins@users.noreply.github.com>

Author: danawoodman

docs/svelte/ssr.md

@@ -42,16 +42,16 @@ If you wish to view the ideal SSR setup, please have a look at the [SSR example]
 Together with SvelteKit's [`load`](https://kit.svelte.dev/docs/load), you can pass the data loaded server-side into `createQuery`'s' `initialData` option:
 
 **src/routes/+page.ts**
-```ts
-import type { PageLoad } from './$types'
 
-export const load: PageLoad = async () => {
+```ts
+export async function load() {
   const posts = await getPosts()
   return { posts }
 }
 ```
 
 **src/routes/+page.svelte**
+
 ```svelte
 <script>
   import { createQuery } from '@tanstack/svelte-query'
@@ -88,7 +88,7 @@ Svelte Query supports prefetching queries on the server. Using this setup below,
 import { browser } from '$app/environment'
 import { QueryClient } from '@tanstack/svelte-query'
 
-export const load = async () => {
+export async function load() {
   const queryClient = new QueryClient({
     defaultOptions: {
       queries: {
@@ -119,9 +119,7 @@ export const load = async () => {
 **src/routes/+page.ts**
 
 ```ts
-import type { PageLoad } from './$types'
-
-export const load: PageLoad = async ({ parent, fetch }) => {
+export async function load({ parent, fetch }) {
   const { queryClient } = await parent()
 
   // You need to use the SvelteKit fetch function here