[docs] Outdated ISR guide?

Which project does this relate to?

Start

Describe the bug

I tried to implement ISG following the ISG guide, and it refers to prerender.routes option in tanstackStart() all the time:

import { tanstackStart } from '@tanstack/react-start/plugin/vite'
import { defineConfig } from 'vite'

export default defineConfig({
  plugins: [
    tanstackStart({
      prerender: {
        routes: ['/blog', '/blog/posts/*'],
        crawlLinks: true,
      },
    }),
  ],
})

This seems wrong, because prerender schema doesn't have a routes field:

https://github.com/TanStack/router/blob/689d88e04c48ec76a18453ab8b82d8d58f2668b6/packages/start-plugin-core/src/schema.ts#L270-L284

Should the ISG guide document the prerender.filter option instead?

Complete minimal reproducer

https://tanstack.com/start/latest/docs/framework/react/guide/isr

Steps to Reproduce the Bug

Check out the ISG Guide

Expected behavior

Correct configuration is documented

Screenshots or Videos

No response

Platform

N/A

Additional context

No response

Open the linked ISG guide and compare its prerender.routes examples with the prerender schema linked in the issue. Update the guide so its configuration matches the supported option, then verify that the documented example is valid and the expected behavior is clear.