Readme Update, leading app change and Automation test for client auth

[akgarg06]

Describe your changes

This PR adds README documentation for the following enhancements:

• Support For Large File Upload #277: Support for Large File Upload
• Use Client Credentials auth instead JWTBearer client credentials #279: Use Client Credentials Authentication instead of JWT Bearer Client Credentials

Additionally, this PR includes:

• annotation required to enable Client Credentials authentication in leading applications footnotes section.
• Automation tests covering the Client Credentials authentication flow as it had dependency on app changes