text: Title: Automatically generate the `docs/api/internal/*.rst` files
  Body: These files need to be manually kept in sync which is a lot of work and error-prone. Would be better to maintain the project's entire API docs in a more automated way
  
  ---
  
  The ridgeplot [API docs](https://ridgeplot.readthedocs.io/en/latest/api/) include a `Internals` section that should include the entire project's documentation
  
  <img width="1182" alt="image" src="https://github.com/user-attachments/assets/0ec5c984-acbf-4cc8-8777-d2eafd52c25e">
  
  Currently, each sub-package (e.g. `ridgeplot._color`) is documented in a separate page.
  
  <img width="1477" alt="image" src="https://github.com/user-attachments/assets/a52ba2f6-745b-4c4d-8944-bd311dca5147">
  
  However, this does not need to be the case. I am okay (and maybe even prefer) if we list all modules in the main API doc page and then a single doc page per module. i.e.,
  
  - [ridgeplot._color](https://ridgeplot.readthedocs.io/en/latest/api/internal/color.html)
    - [ridgeplot._color.colorscale](https://ridgeplot.readthedocs.io/en/latest/api/internal/_color/colorscale.html)
    - [ridgeplot._color.css_colors](https://ridgeplot.readthedocs.io/en/latest/api/internal/_color/css_colors.html)
    - [ridgeplot._color.interpolation](https://ridgeplot.readthedocs.io/en/latest/api/internal/_color/interpolation.html)
    - [ridgeplot._color.utils](https://ridgeplot.readthedocs.io/en/latest/api/internal/_color/utils.html)
  - [ridgeplot._figure_factory](https://ridgeplot.readthedocs.io/en/latest/api/internal/figure_factory.html)
  - [ridgeplot._hist](https://ridgeplot.readthedocs.io/en/latest/api/internal/hist.html)
  - [ridgeplot._kde](https://ridgeplot.readthedocs.io/en/latest/api/internal/kde.html)
  - [ridgeplot._missing](https://ridgeplot.readthedocs.io/en/latest/api/internal/missing.html)
  - [ridgeplot._obj](https://ridgeplot.readthedocs.io/en/latest/api/internal/obj.html)
    - [ridgeplot._obj.traces](https://ridgeplot.readthedocs.io/en/latest/api/internal/_obj/traces.html)
  - [ridgeplot._types](https://ridgeplot.readthedocs.io/en/latest/api/internal/types.html)
  - [ridgeplot._utils](https://ridgeplot.readthedocs.io/en/latest/api/internal/utils.html)
  
  --- 
  
  The way that we currently implement and maintain the current solution is to represent the package structure and modules in RST files, with each RST file containing a `.. automodule:: ridgeplot._color.css_colors` directive.
  
  <img width="279" alt="image" src="https://github.com/user-attachments/assets/45c31693-4340-4577-a367-832b627007f3">
  
  
  Note that currently each module contains a short description inside each RST file (e.g., _"Continuous colorscale utilities."_ for `ridgeplot._color.colorscale`). This could probably be represented as a module docstring when considering a more automated approach.
  
  --
  
  The solution to this problem is not clear to me. Maybe there are already tools out there that solve this nicely (e.g. `sphinx.ext.autodoc`, `sphinx.ext.autosummary`, `sphinx_toolbox.more_autodoc`, etc...). We could take a look at other prominent projects in the Python open-source space that currently use Sphinx and autodoc for API documentation.