Clarify that the project implements *parts* of the OpenSubsonic API. Add
a section detailing the current status and explicitly list implemented
features. Update installation steps to include installing the Diesel
CLI. Add an example for the `createUser.view` endpoint.
This commit introduces the README.md file for the SoundSonic project.
It provides a comprehensive overview of the project, its features,
technologies used, installation instructions, API endpoints, user roles,
configuration details, development guidance, supported extensions,
license,
contributing guidelines, and acknowledgments.