fix: Use absolute URLs for language selector links

Changed relative links (README.zh-CN.md) to absolute GitHub URLs
so they work correctly on PyPI, GitHub, and any other platform
that displays the README.

This fixes the broken Chinese link in the language selector.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

README.md

@@ -2,7 +2,7 @@
 
 # Skill Seeker
 
-English | [简体中文](README.zh-CN.md)
+English | [简体中文](https://github.com/yusufkaraaslan/Skill_Seekers/blob/main/README.zh-CN.md)
 
 [![Version](https://img.shields.io/badge/version-2.7.3-blue.svg)](https://github.com/yusufkaraaslan/Skill_Seekers/releases/tag/v2.7.3)
 [![License: MIT](https://img.shields.io/badge/License-MIT-yellow.svg)](https://opensource.org/licenses/MIT)