Add a note about using redirect with server functions

[amirhhashemi]

This is complementary to #1385.

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[LadyBluenotes]

Suggested change

	Once a response starts streaming, its headers (including the status code and cookies) are immediately sent to the client and **cannot be modified**.
	Any server-side operation that changes headers, such as performing a redirect (`3xx` status) or using APIs like `useSession` that modify cookies, must happen **before** streaming begins.
	Otherwise, you'll encounter errors like:
	Once streaming begins, response headers (including status and cookies) are sent and cannot be changed.
	Any header-modifying logic, such as redirects or APIs that set cookies, must run before streaming starts, or an error will occur.

[amirhhashemi]

I updated it with two changes:

1. I kept useSession as an example. It's a very common source of the error.
2. I mentioned that this only happens when the logic is executed on the server.

[LadyBluenotes]

Suggested change

	**"Cannot set headers after they are sent to the client."**
	To avoid this, disable streaming for queries that may modify headers by enabling the [`deferStream`](/solid-router/reference/data-apis/create-async#deferstream) option.
	```tsx
	const user = createAsync(() => getCurrentUserQuery(), { deferStream: true });
	```
	To avoid this, disable streaming for queries that may modify headers by enabling the [`deferStream`](/solid-router/reference/data-apis/create-async#deferstream):
	```tsx
	const user = createAsync(() => getCurrentUserQuery(), { deferStream: true });

[amirhhashemi]

I think we should keep the error message. It's a common and vague message, and people might try to search it in the docs.