[DOC] Use a different documentation theme

[teald]

Description

There are issues with implementing better accessibility features, such as

• dark mode (see [DOC] Accessibility issues in dark mode #29)
• There doesn't seem to be much documentation of how/if ReadTheDocs considers accessibility on its platform
  • I need to do more research here, but a relatively deep search hasn't yielded anything yet.

While this may be as simple as implementing a style sheet and calling it a day, I worry there are other accessibility issues that the RTD theme does not have the resources to deal with in the near future. If it does become a matter of using different CSS then it may be worth opening a PR there (assuming it's compatible).

Solution

[If applicable, your solution to the issue]

Urgency

• This problem should be fixed quickly (urgent)
• This problem is minor/does not require immediate fixing.