Update Model Derivative Postman Collection documentation to Match Recent Sidebar Changes on APS Dev Portal

[JayanathP]

This Pull Request updates the Model Derivative Postman Collection documentation to reflect the recent changes made to the sidebar navigation on the APS Development Portal. The updated documentation includes:

• Revised content: Ensures that the content accurately aligns with the new sidebar structure.
• Updated images: Replaces existing images with updated versions that reflect the current sidebar layout.

By incorporating these changes, the Model Derivative Postman Collection documentation will remain consistent with the Dev Portal's interface and provide a seamless user experience.