docs: add documentation for linear search

[Saswat-Iare25]

Added documentation and clarifying comments to the linear search exaple (no functional/algorithmic changes)

Description of Change

This PR adds documentation and clarifying comments to the linear search implementation without changing its behavior

References

Checklist

• Added description of change
• Added file name matches File name guidelines
• Added tests and example, test must pass
• Relevant documentation/comments is changed or added
• PR title follows semantic commit guidelines
• Search previous suggestions before making a new one, as yours may be a duplicate.
• I acknowledge that all my contributions will be made under the project's license.

Notes: Documentation only update for clarity.