Improve readme

[dosorio79]

This pull request updates the README.md to clarify the database design and improve the explanation of the Docker-based build process. The main changes focus on documenting the purpose and scope of the telemetry database and making the frontend build instructions clearer.

Documentation improvements:

• Added a new section describing the database layer, emphasizing that it is used exclusively for telemetry, is append-only, and supports both MongoDB and in-memory storage for flexibility and reproducibility.

Build process clarification:

• Updated the Docker instructions to clarify that the frontend is built within the Docker image, making the build and run process more straightforward.