ENH - Add logo and favicon to docs

[trallard]

!NOTE
I started this PR off the branch in #65, so that PR must be merged before this one

This PR:

• Moves the logo and favicon one level up in the _static directory so that this can be rendered by Sphinx book
• Updates the paths to the favicon and logo on the landing page
• Changes the URL to the tutorial to relative URLs (was pointing to the built RTD docs)
• Updates the contribution guidelines to point to the right source directory
• Removes some accidentally checked files (doctrees)

🔗 Link to PR preview: https://jax-ai-stack--114.org.readthedocs.build/en/114/

[pavithraes]

Thanks, Tania. Looks good to me. :)

[jakevdp]

What's the purpose of moving all the files here? This is going to cause conflicts with every other in-flight PR, so I'd lean toward not merging this change.

Can we add the logo and favicon without modifying the file structure of the repo?

[trallard]

I actually branched off #65

Which added the logo, styling, the landing page and changes the docs structure - I am unsure why that change was made there, but I assumed that had been discussed when opening #65.

We can add the logo and favicon without changing the structure of the repo but we'd need to then revert the changes in #65 for this purpose.

[jakevdp]

Ah, got it. In that case we need to wait for #65 to be merged, at which point we can rebase this and the diff should be small.

[jakevdp]

OK, the style update is merged. Can you rebase this? Thanks!

[trallard]

@jakevdp this is ready to merge.

Also while building locally I noticed the Note on the tutorials index so I changed to an admonition to make it more noticeable

[jakevdp]

Thanks!