Add docstring and type hints to two_sum

[gokul000410]

Description

This pull request adds a detailed docstring and type hints to the two_sum
implementation in the arrays section.

The changes improve code readability and maintainability while keeping the
existing algorithm logic unchanged.

Changes Made

• Added a clear docstring explaining the approach
• Added type hints for better clarity

Checklist

• Code follows repository style guidelines
• No functional changes were made

[mindaugl]

It seems to be not finished, e.g., return statement is missing.

[gokul000410]

It seems to be not finished, e.g., return statement is missing.

No , you can see return statement inside the loop if two sum == target it will return , why inside loop because there is always going to have one valid two sum that's equal to target ,if there is no two sum in the array it will raise the value error at the end this is just optional , because in two sum problem there is always going to have one valid two sum pair