message: [Doc] fix misspelling of NumberKeyboard
diff: @@ -3,10 +3,10 @@ The PasswordInput component is usually used with [NumberKeyboard](#/en-US/compon
  ### Install
  ``` javascript
  -import { PasswordInput, NumberKeyBoard } from 'vant';
  +import { PasswordInput, NumberKeyboard } from 'vant';
  Vue.use(PasswordInput);
  -Vue.use(NumberKeyBoard);
  +Vue.use(NumberKeyboard);
  ```
  ### Usage
  