GH-47685: [Docs][Python] Add nested grouping to Python docs TOC

[Daedalus-Icarus]

Rationale for this change

The left-hand sidebar menu for the Python docs lists 22+ entries in a flat structure, making it hard to skim and navigate. The C++ docs already use nested toctree groupings (Getting Started, User Guide, etc.) which makes the sidebar much more scannable. This was requested in #47685.

Closes #47685

What changes are included in this PR?

• Created 5 new intermediate grouping pages that organize the flat toctree into logical sections:
  • Getting Started: install, getstarted
  • Data and Compute: data, compute, memory, timestamps
  • File Formats and I/O: ipc, filesystems, csv, feather, json, orc, parquet, dataset, flight
  • Data Interchange: numpy, pandas, interchange_protocol, dlpack, extending_types
  • Reference: env_vars, api
• Updated index.rst to reference the grouping pages and set maxdepth: 3 so the sidebar shows the nested structure
• The existing integration.rst and getting_involved entries are reused as-is

Are these changes tested?

Documentation-only change. Can be verified by building the docs with Sphinx.

Are there any user-facing changes?

Yes — the Python docs sidebar navigation will show grouped sections instead of a flat list, improving discoverability.

• GitHub Issue: [Docs][Python] Add more levels of nesting to top-level Python docs #47685

[github-actions]

Thanks for opening a pull request!

If this is not a minor PR. Could you open an issue for this pull request on GitHub? https://github.com/apache/arrow/issues/new/choose

Opening GitHub issues ahead of time contributes to the Openness of the Apache Arrow project.

Then could you also rename the pull request title in the following format?

GH-${GITHUB_ISSUE_ID}: [${COMPONENT}] ${SUMMARY}

or

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See also:

• Other pull requests
• Contribution Guidelines - Contributing Overview

[Daedalus-Icarus]

@AlenkaF Could you please review this PR and share feedback?

[github-actions]

⚠️ GitHub issue #47685 has been automatically assigned in GitHub to PR creator.

[Daedalus-Icarus]

@AlenkaF any progress on this PR? when are you available to review this?

[github-actions]

⚠️ GitHub issue #47685 has been automatically assigned in GitHub to PR creator.

[Daedalus-Icarus]

Hey @AlenkaF. please review this and merge. I am waiting for your response

[Daedalus-Icarus]

@AlenkaF @raulcd Please review this too

[raulcd]

@Desel72 thank you very much for your PRs. We truly appreciate when people takes the time to contribute and help make the project better.
I wanted to point out that your messages are coming of as slightly rude, it is ok to ping a maintainer to review your PRs but this:
"please review this and merge. I am waiting for your response" comes across as demanding.
The maintenance of the project requires a lot of time and effort and some of the contributors take a lot of their free time to help. We juggle a lot of priorities and a small docs improvement, while still takes our time might not be on top of our review queue. Could you be mindful of that when posting a message?

I got the same feeling when reviewing this other PR:

• GH-47696: [Docs] PyCapsule protocol implementation status #49550

[Daedalus-Icarus]

Thank you for the feedback, and I apologize if my messages came across as rude. That wasn’t my intention. I really appreciate the time maintainers spend on reviews, and I’ll be more careful with my wording going forward.