README needs to explain Machine to Machine Applications authorization

[alvincrespo]

Checklist

• I have looked into the Readme and Examples, and have not found a suitable solution or answer.
• I have looked into the API documentation 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.

Description

When trying to create a client and having the proper grants enabled for my application, I still came across this error:

{"error":"access_denied","error_description":"Client is not authorized to access \"https://dev-x3r4mfeuopyc566w.us.auth0.com/api/v2/\". You need to create a \"client-grant\" associated to this API. See: https://auth0.com/docs/api/v2#!/Client_Grants/post_client_grants"} (Auth0::AccessDenied)

This was my implementation of the client:

client = Auth0Client.new(
  client_id: Rails.application.credentials.auth_zero.client_id,
  client_secret: Rails.application.credentials.auth_zero.secret,
  domain: Rails.application.credentials.auth_zero.domain,
)

I re-read the README and missed this part: "and that the application is authorized for the Management API". I assumed that enabling the grant did this as well. After doing some research, I came across this issue that explained the need to authorize the application under "Machine to Machine Applications" in APIS.

This should probably be added to the README as:

To authorize your application for the Management API, please visit Applications > APIs > Machine to Machine Applications and then toggle the Authorize button for the application you're integrating with.

Reproduction

1. Configure the grant for the application
2. Create the Ruby client
3. [Failure]

Additional context

No response

ruby-auth0 version

5.17.0

Ruby version

3.2.2

[alvincrespo]

I'll be submitting a PR for this later today.