fix: fixed structure of samples-echo

[Arindam200]

Description

This PR changes the documentation structure of the sample Echo + Postgres app to follow a more standard structure.

Fixes # (issue)

Changes Made

• Updated the documentation structure.
• Ensured consistency with the established documentation standards.
• Updated content to reflect changes in the document structure.

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue).
• New feature (non-breaking change which adds functionality).
• Breaking change (fix or feature that would cause existing functionality to not work as expected).
• This change requires a documentation update.

How Has This Been Tested?

Please describe the tests that you ran to verify your changes. Provide instructions so we can reproduce. Please also list any relevant details for your test configuration

Additional Context (Please include any Screenshots/gifs if relevant)

...

Checklist:

• My code follows the style guidelines of this project.
• I have performed a self-review of my own code.
• I have made corresponding changes to the documentation.
• I have added corresponding tests.
• Any dependent changes have been merged and published in downstream modules.

[Shashwat79802]

1. Include the examples of how the test and mock yml files look after they are generated.
2. Add the section to run the app via docker.
3. Add ending notes at the end.

Take references from other guides.