Cross references in docs

[justusschock]

This pull request makes several documentation improvements to the Sphinx API docs by ensuring that class inheritance hierarchies are displayed in the generated documentation for key classes, while also updating the default inheritance display setting. The main focus is on making the inheritance structure of important classes more visible and clear for users reading the documentation.

Documentation improvements:

• Added the :show-inheritance: directive to the File, Image, Text, Model, Series, MediaType, PhaseType, MetricValue, and Metrics class documentation in docs/source/api.rst to explicitly show their inheritance hierarchies. [1] [2] [3]

Sphinx configuration update:

• Set the show-inheritance option to False by default in docs/source/conf.py, so inheritance will only be shown where explicitly requested in the API docs.