Fix frechet logcdf comments

[nishant1194]

Resolves #5863.

Description

What is the purpose of this pull request?

This pull request:

• Standardized array indexing style in benchmark.c as suggested.
• Corrected the return value in README.md as suggested.
• Fixed the return value in main.c as suggested

Related Issues

Does this pull request have any related issues?

This pull request:

• resolves Address commit comments (commit a74d773) #5863

Questions

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No.

Other

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No.

Checklist

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• Read, understood, and followed the contributing guidelines.

---

@stdlib-js/reviewers

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[kgryte]

Ref: #5871

[stdlib-bot]

Thank you for working on this pull request. However, we cannot accept your contribution as the issue this pull request seeks to resolve has already been addressed in a different pull request or commit.

Thank you again for your interest in stdlib, and we look forward to reviewing your future contributions.