MINOR: [Docs] Add Timestamp With Offset to canonical extension types status

[esadek]

Rationale for this change

The Timestamp With Offset canonical extension type is missing from the Implementation Status documentation page.

What changes are included in this PR?

This PR adds a row for Timestamp With Offset to the Canonical Extension types table of the Implementation Status documentation page. It shows that the extension type is implemented only in Rust: apache/arrow-rs#8743.

Are these changes tested?

Screenshot from docs running locally:

Are there any user-facing changes?

This is a documentation change.

[github-actions]

Thanks for opening a pull request!

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

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See also:

• Other pull requests
• Contribution Guidelines - Contributing Overview

[esadek]

cc @zeroshade

[rok]

This checks out!
Wanna implement this in C++/Python @esadek? :)

[esadek]

@rok I could give Python a stab once it's been implemented in C++. Haven't written a line of C++ before.

[rok]

@rok I could give Python a stab once it's been implemented in C++. Haven't written a line of C++ before.

Good time to give it a try then! :))
See some examples: #43488, #13901

[conbench-apache-arrow]

After merging your PR, Conbench analyzed the 3 benchmarking runs that have been run so far on merge-commit e183ea9.

There was 1 benchmark result indicating a performance regression:

• Commit Run on amd64-m5-4xlarge-linux at 2026-07-01 15:35:45Z
  • file-write (Python) with compression=uncompressed, dataset=fanniemae_2016Q4, file_type=feather, input_type=table

The full Conbench report has more details. It also includes information about 2 possible false positives for unstable benchmarks that are known to sometimes produce them.