fix: remove unused headers and move misplaced sections

[ChaitraTM]

Resolves #5714.

Description

What is the purpose of this pull request?

This pull request:

-Removes unused <math.h> headers from example.c and main.c
-Moves the misplaced references section to the correct position
-Adds a missing closing tag

Related Issues

Does this pull request have any related issues?

This pull request:

• resolves Address commit comments (commit e63c0b4) #5714

Questions

Any questions for reviewers of this pull request?

No.

Other

Any other information relevant to this pull request? This may include screenshots, references, and/or implementation notes.

No.

Checklist

Please ensure the following tasks are completed before submitting this pull request.

• Read, understood, and followed the contributing guidelines.

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@stdlib-js/reviewers

[Planeshifter]

You also want to check your git. There is currently a submodule which shouldn't be part of this PR.

[ChaitraTM]

I checked, but there are no submodules in my PR (git submodule status returns nothing, and .gitmodules is empty). Could you clarify which file appears as a submodule?

[gururaj1512]

This submodule shouldn't be part of this PR.

[stdlib-bot]

Thank you for working on this pull request. However, we cannot accept your contribution due to Git history issues.

Some common issues include:

• Merge conflicts
• Inappropriate commit messages
• Unrelated commits
• Including changes from merged branches that weren't intended for this PR

We recommend opening a new pull request with only the intended changes.

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