Document consistent directory naming for search and sort algorithms

[thespirits910]

This PR addresses the directory naming inconsistency mentioned in Issue #3 (use of Search/, searching/, and sort/ in older documentation).

The current codebase already uses standardized, lowercase plural package names:

• searches (com.thealgorithms.searches)
• sorts (com.thealgorithms.sorts)

To make this convention explicit for contributors and prevent future inconsistencies, I added a "Naming Conventions" section to DIRECTORY.md that documents:

• The use of lowercase, plural directory names
• The canonical names for searching and sorting algorithms
• That older forms such as Search/, searching/, or sort/ should be avoided

This keeps the project structure clear and consistent and resolves the original concern behind Issue 3.

• I have read 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 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.
✅ Project coverage is 78.87%. Comparing base (a8bc9cc) to head (f07d1df).

Additional details and impacted files

@@            Coverage Diff            @@
##             master    #7161   +/-   ##
=========================================
  Coverage     78.87%   78.87%           
  Complexity     6828     6828           
=========================================
  Files           766      766           
  Lines         22607    22607           
  Branches       4444     4444           
=========================================
  Hits          17831    17831           
  Misses         4064     4064           
  Partials        712      712           

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