Minor issue: Read me references wrong build.gradle

Checklist

[X] The issue can be reproduced in the auth0_flutter sample app (or N/A).
[X] I have looked into the Readme, Examples, and FAQ and have not found a suitable solution or answer.
[X] I have looked into the API documentation and have not found a suitable solution or answer.
[X] I have searched the issues and have not found a suitable solution or answer.
[X] I have searched the Auth0 Community forums and have not found a suitable solution or answer.
[X] I agree to the terms within the Auth0 Code of Conduct.

Description

Hi Auth0 Devs, There is a minor issue in the readme.

The instruction Open the android/build.gradle file and add the following manifest placeholders inside android > defaultConfig.

references the android/build.gradle but typically, flutter projects set their defaultConfig in the android/app/build.gradle so it may be momentarily confusing

Reproduction

Open Read Me

Additional context

No response

auth0_flutter version

^1.2.1

Flutter version

3.7.10

Platform

Web

Platform version(s)