docs: Replace regular fetch with a $fetch from nuxt

This feature was implementet in https://github.com/wobsoriano/trpc-nuxt/pull/28 and describe better way to work with ssr

docs/content/1.get-started/2.usage.md

@@ -98,11 +98,31 @@ export default defineNuxtPlugin(() => {
   const client = createTRPCProxyClient<AppRouter>({
     links: [
       httpBatchLink({
+        url: '/api/trpc',
+        
+        
         /**
-         * If you want to use SSR, you need to use the server's full URL
-         * @link https://trpc.io/docs/ssr
-         **/
-        url: 'http://localhost:3000/api/trpc',
+         * Replace regular `fetch` with a `$fetch` from nuxt
+         *
+         * During server-side rendering, calling $fetch to fetch your internal API routes
+         * will directly call the relevant function (emulating the request),
+         * saving an additional API call.
+         *
+         * @see https://nuxt.com/docs/api/utils/dollarfetch
+         */
+        fetch: (input, options) =>
+          globalThis.$fetch.raw(input.toString(), options)
+            .catch((e) => {
+              if (e instanceof FetchError && e.response)
+                return e.response
+
+              throw e
+            })
+            .then(response => ({
+              ...response,
+              json: () => Promise.resolve(response._data),
+            })),
+            
       }),
     ],
   })