docs: link LoRA Training Tutorials and Side-Step advanced training docs

[ChuxiJ]

• Add LoRA Training Tutorial links to README Train section (4 languages)
• Add LoRA Training column to README multi-language docs table
• Link LoRA Training Tutorial from Tutorial.md (en/zh/ja)
• Link LoRA Training Tutorial from GRADIO_GUIDE.md (en/zh/ja/ko)
• Add Side-Step advanced training section to all 4 LoRA Training Tutorials
• Add Side-Step documentation entry in README Train section

Summary by CodeRabbit

• Documentation
  • Added comprehensive LoRA Training tutorials with step-by-step guidance across multiple languages (English, Chinese, Japanese, Korean)
  • Introduced Side-Step advanced training toolkit documentation including guides for optimization and workflows
  • Enhanced cross-references and links throughout guide documentation
  • Updated README table structure with LoRA Training information and refreshed visual assets

[coderabbitai]

Caution

Review failed

The pull request is closed.

📝 Walkthrough

Walkthrough

This pull request updates documentation across multiple languages (English, Japanese, Korean, Chinese) to promote LoRA training by introducing a dedicated tutorial reference and adding an advanced Side-Step training alternative section. The README is restructured to feature LoRA Training prominently in the language-docs table and update architecture image references.

Changes

Cohort / File(s)	Summary
README restructuring README.md	Adds LoRA Training column to language-docs table, restructures Train section with detailed LoRA Training Tutorial block and Side-Step toolkit note, updates Architecture section image asset reference to ACE-Step_framework.png.
LoRA Training tutorials - all languages docs/en/LoRA_Training_Tutorial.md, docs/ja/LoRA_Training_Tutorial.md, docs/ko/LoRA_Training_Tutorial.md, docs/zh/LoRA_Training_Tutorial.md	Adds new "Advanced Training with Side-Step" section to each language's tutorial with overview of Side-Step toolkit features and comprehensive documentation reference table.
GRADIO guides - all languages docs/en/GRADIO_GUIDE.md, docs/ja/GRADIO_GUIDE.md, docs/ko/GRADIO_GUIDE.md, docs/zh/GRADIO_GUIDE.md	Adds cross-reference links to LoRA Training Tutorial in two locations within each language's GRADIO guide documentation.
Tutorial references - all languages docs/en/Tutorial.md, docs/ja/Tutorial.md, docs/ko/Tutorial.md, docs/zh/Tutorial.md	Replaces simple LoRA training text references with markdown hyperlinks to LoRA Training Tutorial and adds note about Gradio UI one-click training option.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~15 minutes

Poem

🐰 A LoRA path now shines so bright,
With Side-Step toolkit in sight,
Cross-referenced guides in every tongue,
Documentation wonders, freshly sung! ✨

✨ Finishing touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch docs/link-lora-training-tutorials

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