fix: CrawlerRunConfig docstring in Link/Domain Handling section

[hyeongmin90]

Summary

Fixed duplicate exclude_internal_links parameter entry and added missing preserve_https_for_internal_links parameter in CrawlerRunConfig docstring.

List of files changed and why

• crawl4ai/async_configs.py - Removed duplicate exclude_internal_links entry and added missing preserve_https_for_internal_links parameter in CrawlerRunConfig docstring

How Has This Been Tested?

Documentation-only changes. Verified by comparing the async_configs.py docstring against the actual parameters in the Link/Domain Handling section.

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added/updated unit tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes