Fix skill-creator usage instructions: Use natural conversation, not script paths

The previous instructions showed incorrect direct script paths like:
  skill-creator/scripts/init_skill.py <skill-name> --path <output-dir>

These paths don't work after marketplace installation because:
1. Users install via: /plugin marketplace install daymade/claude-code-skills#skill-creator
2. Skills are installed to ~/.claude/skills/, not the user's current directory
3. skill-creator is a SKILL that guides Claude Code, not a standalone CLI tool

Correct usage:
After installing skill-creator, users simply ask Claude Code in natural language:
  "Create a new skill called my-awesome-skill in ~/my-skills"
  "Validate my skill at ~/my-skills/my-awesome-skill"
  "Package my skill at ~/my-skills/my-awesome-skill"

Claude Code, with skill-creator loaded, knows how to execute the bundled scripts
and guide users through the entire skill creation process.

Fixed in:
- README.md (English)
- README.zh-CN.md (Chinese)
- scripts/install.sh (bash)
- scripts/install.ps1 (PowerShell)

README.md

@@ -55,16 +55,17 @@ The `skill-creator` is the **meta-skill** that enables you to build, validate, a
 
 ### What You Can Do
 
-```bash
-# Initialize a new skill from template
-skill-creator/scripts/init_skill.py my-awesome-skill --path ~/my-skills
+After installing skill-creator, simply ask Claude Code:
 
-# Validate your skill structure and quality
-skill-creator/scripts/quick_validate.py ~/my-skills/my-awesome-skill
-
-# Package your skill for distribution
-skill-creator/scripts/package_skill.py ~/my-skills/my-awesome-skill
 ```
+"Create a new skill called my-awesome-skill in ~/my-skills"
+
+"Validate my skill at ~/my-skills/my-awesome-skill"
+
+"Package my skill at ~/my-skills/my-awesome-skill for distribution"
+```
+
+Claude Code, with skill-creator loaded, will guide you through the entire skill creation process - from understanding your requirements to packaging the final skill.
 
 📚 **Full documentation**: [skill-creator/SKILL.md](./skill-creator/SKILL.md)