Add documentation theme for each documentation engine

[xmnlab]

Summary

Add documentation theme for each documentation engine, the options would be exclusive for each engine.

Additional Information

Code of Conduct

• I agree to follow the Code of Conduct

[YurelyCamacho]

@xmnlab This means that after selecting the documentation engine, the user can select among several themes the one he/she prefers or have a default one for each documentation engine.
Currently mkdocs uses material theme and sphinx has html_theme = "sphinx_rtd_theme".

[xmnlab]

For those which it has just one option we can have just that as default .. otherwise we should show the options.

Doea it make sense?

[YurelyCamacho]

@xmnlab I understand that the one with more than one option is sphinx? md or rst. Is that what you mean?
I also believe that this will depend on the resolution of issue #28 which in turn depends on issue #171.
Is that so?

[xmnlab]

not exactly related to #28, but for sure it depends on #171
we could have multiple themes for each doc engine ... for example the pydata sphinx theme
although we planned #171 for gsoc, but maybe I will need to move that forward to unblock the other tasks

[YurelyCamacho]

@xmnlab Perfect, right now this issue is assigned in the PSF grant to Anavelyz

[xmnlab]

Oh you are right! So let's wait for @Anavelyz then <3