[DOCS] create custom api doc templates

[henrydingliu]

the api pages appear to be generated using sphinx default templates, which contains a method summary. the summary is meant to link to individual pages for each method. however, this is overkill for our repo. a custom template will allow us to forgo the method summary, and simply list all methods on the same page.

this should be done before we get to api docstrings at the method level, as those aren't currently shown in the method summary tables.

[henrydingliu]

@priyam0k would you be interested in tackling this?

[priyam0k]

On it. I added real templates under _templates/autosummary/ so methods show inline instead of as a summary table.

[priyam0k]

Opened #885 for this. Added custom autosummary templates so methods/properties show inline on the class page instead of a summary table. One open call in there: Triangle inherits a bunch of sklearn methods (get_params, set_output, etc.) — let me know if you want those shown or hidden.