Add Chinese translation of js-spread

This chapter is pretty interesting, 'Spread/Rest Attributes' has not got a formal term in Chinese.
Personal I translate 'Rest' to '留余', which sounds written word.
'Spread' to '展开' which is used by Mozilla's doc. [Spread Operator in Chinese](https://developer.mozilla.org/zh-CN/docs/Web/JavaScript/Reference/Spread_operator) vs [Spread Operator in English](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Spread_operator)