Renewing perception metrics documentation

[tejasstanley]

The current documentation is split between the human-readable docs at https://jderobot.github.io/PerceptionMetrics/ and the docstring-driven API docs at https://jderobot.github.io/PerceptionMetrics/py_docs/build/html/index.html.

Combining these into a clearer documentation structure would make it easier for users to find guides for datasets, models, CLI usage, metrics, and data formats, while still keeping the detailed Python API reference available.

Reference style:
https://carla.readthedocs.io/en/latest/python_api/

[Sanketjadhav31]

Hello!
It would be great if you allow me to handle this problem.
I will go through the existing documents and try to make some changes in terms of their organization. Could you please provide me with any guidelines prior to that?