fix: Readme changes for App registration

[Kingshuk-Microsoft]

Purpose

This pull request updates documentation to clarify authentication setup steps for Azure deployments. The most important changes include improved instructions for configuring authentication providers and correcting manual app registration steps.

Authentication configuration improvements

• Updated instructions in ConfigureAppAuthentication.md to clarify how to add redirect URIs and grant admin consent for permissions, including verification steps. [1] [2]
• Added a new section in ManualAppRegistrationConfiguration.md detailing how to enable ID tokens for the application, improving clarity for manual app registration.
• Corrected the redirect URI example in manual registration documentation to use the proper .auth path.
• Fixed step numbering and order for tenant ID retrieval and authentication setup in the manual registration guide.

Does this introduce a breaking change?

• Yes
• No

What to Check

Verify that the following are valid

• Check the deployment guide and manual app registration.
• Deploy accelerator and use manual app registration.