Improve documentation and readability in LinearSearch

[madhavisolanki-ui]

• I have read [CONTRIBUTING.md](https://github.com/TheAlgorithms/Java/blob/master/CONTRIBUTING.md).
• This pull request is all my own work -- I have not plagiarized it.
• All filenames are in PascalCase.
• All functions and variable names follow Java naming conventions.
• All new algorithms have a URL in their comments that points to Wikipedia or other similar explanations.
• All new algorithms include a corresponding test class that validates their functionality.
• All new code is formatted with clang-format -i --style=file path/to/your/file.java

Changes made:

• Improved return description for better clarity
• Minor readability improvements in the code

[codecov-commenter]

Codecov Report

❌ Patch coverage is 0% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 79.49%. Comparing base (79bc620) to head (f93fc72).

Files with missing lines	Patch %	Lines
.../java/com/thealgorithms/searches/LinearSearch.java	0.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #7378      +/-   ##
============================================
- Coverage     79.50%   79.49%   -0.01%     
+ Complexity     7161     7159       -2     
============================================
  Files           797      797              
  Lines         23409    23409              
  Branches       4603     4603              
============================================
- Hits          18611    18609       -2     
  Misses         4054     4054              
- Partials        744      746       +2     

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