[Bug Report]: Request for document update

[yasuki0707]

Steps to reproduce

1. Visit this page
2. Check the content of farm.config.ts

Reproduce link

No response

What is actually happening?

farm.config.ts is currently configured using externals key in defineConfig(), but this key is not valid one, external should be used instead.

System Info

System:
    OS: macOS 15.6.1
    CPU: (10) arm64 Apple M1 Max
    Memory: 67.27 MB / 32.00 GB
    Shell: 5.9 - /bin/zsh
  Binaries:
    Node: 23.7.0 - /opt/homebrew/bin/node
    npm: 10.9.2 - /opt/homebrew/bin/npm
    pnpm: 9.15.0 - /opt/homebrew/bin/pnpm
  Browsers:
    Chrome: 142.0.7444.176
    Safari: 18.6
  npmPackages:
    @farmfe/core: ^1.7.11 => 1.7.11