GitHub connection scopes documentation

[willvedd]

Description

Issue #177 highlighted some confusion around configuring scopes for Github connections. The Go SDK appears to perform some conversions so the names of the scopes aren't quite obvious. Adding a validation function here is not possible because the Terraform provider SDK does not support it for lists and sets so documentation will need to suffice.

Checklist

Note: Checklist required to be completed before a PR is considered to be reviewable.

Auth0 Code of Conduct

• I have read and agreed to the terms within the Auth0 Code of Conduct

Auth0 General Contribution Guidelines

• I have read the Auth0 General Contribution Guidelines

Changes include test coverage?

• Yes
• Not needed

Does the description provide the correct amount of context?

• Yes, the description provides enough context for the reviewer to understand what these changes accomplish

Have you updated the documentation?

• Yes, I've updated the appropriate docs
• Not needed

Is this code ready for production?

• Yes, all code changes are intentional and no debugging calls are left over