Update two_num.py

[dnoice]

.### Summary
This commit improves the twoSum function by enhancing readability, adhering to Python's PEP 8 guidelines, and improving modularity. The refactored code is now cleaner, easier to maintain, and better suited for future enhancements.

Changes

• Renamed twoSum → two_sum to align with PEP 8 naming conventions.
• Improved the docstring to follow PEP 257 standards with clear descriptions, examples, and argument details.
• Replaced the inline print() statement with a proper return value, ensuring the function behaves as expected when integrated into larger projects.
• Enhanced variable naming by replacing compl with complement for improved clarity.
• Added a main block for controlled script execution, making the code more modular and easier to test.
• Improved the return logic by explicitly returning False when no valid pair is found, ensuring clearer outcomes for edge cases.

Rationale

These changes prioritize:

• Improved readability for future maintainers.
• Clearer logic to reduce ambiguity in variable names and return behavior.
• Better code structure by separating functional logic from I/O actions.

Impact

• The function's behavior remains identical for expected use cases.
• Code is now more Pythonic, modular, and maintainable.
• The improved structure sets a stronger foundation for future enhancements, such as unit tests or expanded functionality.