update docs

playground/plugins/trpc-client.ts

@@ -3,6 +3,7 @@ import superjson from 'superjson'
 import type { AppRouter } from '~~/server/trpc/routers'
 
 export default defineNuxtPlugin(() => {
+  const headers = useRequestHeaders()
   const client = createTRPCProxyClient<AppRouter>({
     transformer: superjson,
     links: [
@@ -13,7 +14,12 @@ export default defineNuxtPlugin(() => {
           (opts.direction === 'down' && opts.result instanceof Error)
       }),
       httpBatchLink({
-        url: 'http://localhost:3000/api/trpc'
+        url: 'http://localhost:3000/api/trpc',
+        headers () {
+          return {
+            ...unref(headers)
+          }
+        }
       })
     ]
   })