docs: Add ASF attribution

[simicd]

Which issue does this PR close?

Closes #553

Rationale for this change

Aligning Apache Software Foundation attribution across projects

What changes are included in this PR?

• Add ASF footer
• Update docs requirements.txt (align with arrow-datafusion)
• Fix issues preventing docs compilation
• Update docs README, adding more precise instructions on how to run sphinx build

Are there any user-facing changes?

Updated footer on documentation website

[andygrove]

Thanks @simicd but could we just do the documentation changes in this PR rather than make functional changes to the code as well?

[simicd]

Thanks for the feedback @andygrove, sure will do that. Background: The changes were required to make it work (on Windows, not sure if Linux has those issues too):

• Initially I couldn't pip install requirements-310.txt because Datafusion 0.35.0 seems to rely on pyarrow >= 11.0, the current requirements-310.txt still lists pyarrow 6.0
• Once I added that one of the unit tests failed in CI
• The sphinx command would fail because the use of pipes in Python docstrings (|n|) seems not to be allowed so I escaped it

So I thought I leave these changes in to make the builds reproducible. I will now limit the changes to docs only and raise a separate ticket & PR for the remaining issue(s).

[simicd]

Undid the changes that are not directly related to docs, please let me know if you have any further suggestions!