Unset default list style

[Privat33r-dev]

Clean up unnecessary symbols, leading to improvement in the content readability.
Before:

After:

Preview: https://python-docs-theme-previews--179.org.readthedocs.build/en/179/tutorial/index.html

Before: https://python-docs-theme-previews.readthedocs.io/en/latest/tutorial/index.html

[hugovk]

Please could post example before and after screenshots, with links?

This PR has a preview at https://python-docs-theme-previews--179.org.readthedocs.build/en/179/ (shown in the status checks).

For the before, it's probably best to use https://python-docs-theme-previews.readthedocs.io, which has the recent font change (as the font change hasn't been deployed to https://docs.python.org yet).

Thanks!

[Privat33r-dev]

@hugovk thanks for the reminder, I thought about it, but somehow it slipped my mind (after adventure with git, I guess).

[hugovk]

Git is the adventure that keeps giving :)

Unfortunately this PR also removes bullets in places like this:

https://python-docs-theme-previews.readthedocs.io/en/latest/library/asyncio.html

->

https://python-docs-theme-previews--179.org.readthedocs.build/en/179/library/asyncio.html

[Privat33r-dev]

Frankly, it doesn't work that well in many places, thanks for pointing that out :) I will rethink this approach, maybe I will come back with a better approach later.

Currently it still has problems in places like:
https://python-docs-theme-previews--179.org.readthedocs.build/en/179/glossary.html#term-parameter
etc.