Doc updating

[MubashirullahD]

Checklist

• I have looked into the Readme and have not found a suitable solution or answer.
• I have searched the issues and have not found a suitable solution or answer.
• I have searched the Auth0 Community forums and have not found a suitable solution or answer.
• I agree to the terms within the Auth0 Code of Conduct.

Describe the problem you'd like to have solved

I started with the normal application setup flow and choose SPA React but when I came to step 4 where we test this sample app, I wasted hours because when I clicked on login, it would say not authorised. It's only after looking at the doc I learn I need to set the authentication method to none. So, long story short, the flow is broken. This missing step either needs to be part of the onboarding where it mentions the local host redirects being added or it should be added in the read me here.
I also noticed the docs referring to using npm and yet its yarn in the project.

Describe the ideal solution

Update readme with other essential steps to test the demo. Some of those steps are currently mentioned in onboarding and some steps are missing.

Alternatives and current workarounds

To make this demo work, people need to go to the Application, the credentials and set the Authentication Method to None. Only then will this app work.

Additional context

No response