Add how-to-release guide

[tscholak]

✨ Description

Adds a guide that explains how we release new versions of Fast-LLM.

🔍 Type of change

Select all that apply:

• 🐛 Bug fix (non-breaking change that addresses a specific issue)
• 🚀 New feature (non-breaking change that adds functionality)
• ⚠️ Breaking change (a change that could affect existing functionality)
• 📈 Performance improvement/optimization (improves speed, memory usage, or efficiency)
• 🛠️ Code refactor (non-functional changes that improve code readability, structure, etc.)
• 📦 Dependency bump (updates dependencies, including Dockerfile or package changes)
• 📝 Documentation change (updates documentation, including new content or typo fixes)
• 🔧 Infrastructure/Build change (affects build process, CI/CD, or dependencies)

📝 Changes

Add How-to-Release guide.

[tscholak]

Hi @jlamypoirier, I am interested in documenting and setting up a complete release workflow. Can you please review this guide and provide feedback?
I'd also like us to tag and push a release for 0.2.0 based on these instructions.