Adds incubator logo and ASF info for #1346

[skrawcz]

This implements #1346 in the quickest way possible. This shoves things into the footer, and then also into the left hand nav-bar.

There is a way to create a splash page with the sphinx furo theme, but I didn't explore that.

Changes

• adds incubator logo
• adds footer to docs (works in dark & light mode)
• adds links to ASF on left hand side

How I tested this

• locally built it

Notes

Checklist

• PR has an informative and human-readable title (this will be pulled into the release notes)
• Changes are limited to a single goal (no scope creep)
• Code passed the pre-commit check & code is left cleaner/nicer than when first encountered.
• Any change in functionality is tested
• New functions are documented (with a description, list of inputs, and expected output)
• Placeholder code is flagged / future TODOs are captured in comments
• Project documentation has been updated if adding/changing functionality.