docs: new light/dark mode toggle breaks logo in docs

Description

The change from #205, though successful when viewed on GitHub, breaks the Jumanji logo in MkDocs:

It seems that MkDocs is not correctly updating paths. Consider one of the other images on the page in README.md, e.g.:

<img src="docs/env_anim/bin_pack.gif" alt="BinPack" width="16%">

Notice that the image source is prefixed with the docs folder, src=docs/.... But when the docs are built, the resulting index.html:

<img src="env_anim/bin_pack.gif" alt="BinPack" width="16%">

That is, the docs/ prefix is correctly removed.

Yet with the dark/light logo, defined in README.md as:

<p align="center">
<picture>
  <source media="(prefers-color-scheme: dark)" srcset="docs/img/jumanji_logo_dm.png">
  <source media="(prefers-color-scheme: light)" srcset="docs/img/jumanji_logo.png">
  <img alt="Jumanji Logo" src="docs/img/jumanji_logo.png", width="50%">
</picture>
</p>

the resulting paths are not updated in index.html:

<p align="center">
<picture>
  <source media="(prefers-color-scheme: dark)" srcset="docs/img/jumanji_logo_dm.png">
  <source media="(prefers-color-scheme: light)" srcset="docs/img/jumanji_logo.png">
  <img alt="Jumanji Logo" src="docs/img/jumanji_logo.png", width="50%">
</picture>
</p>

hence the missing logo.

Additionally, note: even if we fix the src location issue, we may need to add custom CSS to handle prefers-color-scheme. MkDocs Material has gone for an approach where you append a hash fragment to the url, but GitHub has deprecated such an approach, in favour of what was done in #205.

(Issue found by @djbyrne.)

What Jumanji version are you using?

v0.3.1

Which accelerator(s) are you using?

n/a

Additional System Info

No response

Additional Context

No response

(Optional) Suggestion

No response

instadeepai / jumanji