docs: add edge cases to BinarySearch documentationFinal binary doc

[prashantpiyush1111]

Added an Edge Cases section to the BinarySearch JavaDoc to improve clarity for beginners.

This includes handling of:

• null and empty arrays
• null keys
• element not found cases
• single element arrays
• duplicate elements

[codecov-commenter]

Codecov Report

❌ Patch coverage is 93.54839% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 79.55%. Comparing base (b3e31b5) to head (ddd2479).

Files with missing lines	Patch %	Lines
.../java/com/thealgorithms/searches/BinarySearch.java	85.71%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #7385      +/-   ##
============================================
+ Coverage     79.53%   79.55%   +0.01%     
- Complexity     7176     7184       +8     
============================================
  Files           798      799       +1     
  Lines         23467    23484      +17     
  Branches       4617     4617              
============================================
+ Hits          18665    18682      +17     
  Misses         4055     4055              
  Partials        747      747              

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