• Add an algorithm
• Fix a bug or typo in an existing algorithm
• Documentation change

Description:
This pull request adds algorithms for 2Sum, 3Sum, Kadane's Algorithm, and linked list problems including finding the intersection point and implementing the slow-fast pointer technique.

1. 2Sum Algorithm: Finds two numbers in an array that add up to a specified target sum using a hash map for efficient lookups.
2. 3Sum Algorithm: Identifies all unique triplets in the array that sum to zero.
3. Kadane's Algorithm: Efficiently computes the maximum sum of a contiguous subarray.
4. Linked List Problems:
   • FindIntersectionPoint: Determines the intersection point of two linked lists.
   • SlowFast: Implements the slow-fast pointer technique to detect cycles in a linked list.

Checklist:

• I have read CONTRIBUTING.md.
• This pull request is all my own work -- I have not plagiarized.
• I know that pull requests will not be merged if they fail the automated tests.
• This PR only changes one algorithm file. To ease review, please open separate PRs for separate algorithms.
• All new JavaScript files are placed inside an existing directory.
• All filenames use the UpperCamelCase (PascalCase) style. There should be no spaces in filenames.
  Example: UserProfile.js is allowed but userprofile.js, Userprofile.js, user-Profile.js, userProfile.js are not.
• All new algorithms have a URL in their comments that points to Wikipedia or another similar explanation.
• If this pull request resolves one or more open issues, then the commit message contains Fixes: #{$ISSUE_NO}. (Replace {$ISSUE_NO} with the actual issue number if applicable)
  .