docs: improve docs

docs/content/1.get-started/4.tips/2.headers.md

@@ -0,0 +1,44 @@
+---
+title: Headers
+---
+
+# Headers
+
+We can use the built-in [useRequestHeaders](https://v3.nuxtjs.org/api/composables/use-request-headers/) to set outgoing request headers:
+
+::alert{type="info"}
+[createTRPCNuxtClient](/get-started/client/create) has this feature by default.
+::
+
+```ts [plugins/client.ts]
+export default defineNuxtPlugin(() => {
+  const headers = useRequestHeaders()
+
+  const client = createTRPCProxyClient<AppRouter>({
+    links: [
+      httpBatchLink({
+        // headers need to be a function so it gets called dynamically
+        // every HTTP request
+        headers() {
+          // You can add more custom headers here
+          return headers
+        }
+      }),
+    ],
+  })
+
+  return {
+    provide: {
+      client,
+    },
+  }
+})
+```
+
+```ts [server/trpc/context.ts]
+export function createContext (event: H3Event) {
+  console.log('cookies', parseCookies(event))
+
+  return {}
+}
+```