Function capitalize

capitalize(s: string): string
First letter uppercase, other lowercase

首字母大写，其余小写
Parameters
- s: string
  The string to capitalize. 要首字母大写的字符串
Returns string
The capitalized string. 首字母大写的字符串
Example
```
capitalize('hello') // 'Hello'
capitalize('WORLD') // 'World'
```
- Defined in src/string/capitalize.ts:17