Should update boilerplate docs for newer node.js / yarn

- Now there are no "two giant buttons" in Node.js official site, should change the phrase.
> 現在 Node.js 官方網站已無「兩個巨大的按鈕」，應該修正表述

https://github.com/koishijs/docs/blob/0cd5f59852eb91c34b2130e5de56006f1b4d1ce4/zh-CN/manual/starter/boilerplate.md?plain=1#L31-L37

- Node.js now seems to be shipped with `yarn` (should confirm!) and `corepack`, also generally we recommend using Yarn Berry
> Node.js 目前似乎會連同 `yarn` (需確認) 和 `corepack`，并且我們現在推薦使用 Yarn Berry

https://github.com/koishijs/docs/blob/0cd5f59852eb91c34b2130e5de56006f1b4d1ce4/zh-CN/manual/starter/boilerplate.md?plain=1#L43-L51

Start with zh-CN/manual/starter/boilerplate.md around lines 31–37 and 43–51, following the linked revision for context. Confirm the current Node.js, Corepack, and Yarn Berry guidance, then update the outdated wording and package-management instructions. Done means the boilerplate documentation accurately reflects the current recommendations.

Written by the indexing model from the issue text.