google captcha react snippet missing `useState` import

**Describe the content issue**:
A clear and concise description of what the content issue is. Is there content missing or is there incorrect content?

**URL page where content issue is**:

https://docs.amplify.aws/javascript/tools/cli/usage/lambda-triggers/#custom-auth-challenge-with-google-recaptcha

```
src/App.js
Line 30:41: 'useState' is not defined no-undef
Line 35:9: 'username' is not defined no-undef
Line 36:9: 'password' is not defined no-undef
Line 48:24: 'CaptchaConfirmation' is not defined react/jsx-no-undef
```