MINOR: Fix docstrings for kleene boolean scalar funcs - #13907

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If this is not a minor PR. Could you open an issue for this pull request on JIRA? https://issues.apache.org/jira/browse/ARROW

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

ARROW-${JIRA_ID}: [${COMPONENT}] ${SUMMARY}

or

MINOR: [${COMPONENT}] ${SUMMARY}

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• Other pull requests
• Contribution Guidelines - How to contribute patches

Thanks @gforsyth !

Benchmark runs are scheduled for baseline = a1c3d57 and contender = 1a34a07. 1a34a07 is a master commit associated with this PR. Results will be available as each benchmark for each run completes.
Conbench compare runs links:
[Finished ⬇️0.0% ⬆️0.0%] ec2-t3-xlarge-us-east-2
[Failed ⬇️1.05% ⬆️0.14%] test-mac-arm
[Failed ⬇️6.58% ⬆️0.0%] ursa-i9-9960x
[Finished ⬇️1.35% ⬆️0.57%] ursa-thinkcentre-m75q
Buildkite builds:
[Finished] 1a34a078 ec2-t3-xlarge-us-east-2
[Finished] 1a34a078 test-mac-arm
[Failed] 1a34a078 ursa-i9-9960x
[Finished] 1a34a078 ursa-thinkcentre-m75q
[Finished] a1c3d57a ec2-t3-xlarge-us-east-2
[Failed] a1c3d57a test-mac-arm
[Failed] a1c3d57a ursa-i9-9960x
[Finished] a1c3d57a ursa-thinkcentre-m75q
Supported benchmarks:
ec2-t3-xlarge-us-east-2: Supported benchmark langs: Python, R. Runs only benchmarks with cloud = True
test-mac-arm: Supported benchmark langs: C++, Python, R
ursa-i9-9960x: Supported benchmark langs: Python, R, JavaScript
ursa-thinkcentre-m75q: Supported benchmark langs: C++, Java

['Python', 'R'] benchmarks have high level of regressions.
ursa-i9-9960x