Improve comments, add function documentation in BinarySearch2dArray.java

[Hardvan]

• [x] I have read CONTRIBUTING.md.
• [x] This pull request is all my own work -- I have not plagiarized it.
• [x] All filenames are in PascalCase.
• [x] All functions and variable names follow Java naming conventions.
• [x] All new algorithms have a URL in their comments that points to Wikipedia or other similar explanations.
• [x] All new code is formatted with clang-format -i --style=file path/to/your/file.java

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 52.84%. Comparing base (ce6d98f) to head (d0ccec4).

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #5518      +/-   ##
============================================
+ Coverage     52.82%   52.84%   +0.01%     
  Complexity     3306     3306              
============================================
  Files           529      529              
  Lines         15361    15361              
  Branches       2926     2926              
============================================
+ Hits           8115     8117       +2     
+ Misses         6912     6911       -1     
+ Partials        334      333       -1     

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[Hardvan]

Thanks!