feat: Added documentation for Mirai theme data

[i-asimkhan]

Description

Added documentation for Mirai theme data

Related Issues

#170

Type of Change

• [ ] New feature (non-breaking change which adds functionality)
• [ ] Bug fix (non-breaking change which fixes an issue)
• [ ] Breaking change (fix or feature that would cause existing functionality to change)
• [ ] Code refactor
• [ ] Build configuration change
• [X] Documentation
• [ ] Chore