Adding SyntaxKit

[leogdion]

• Project Name: SyntaxKit
• Project URL: https://github.com/brightdigit/SyntaxKit
• Project Description: Generate Swift code programmatically with a declarative syntax.
• Why it should be added to awesome-swift:
• At least 15 stars (GitHub project)
• Support Swift 5 Swift 6
• Updated contents.json instead of README
• Lib is fully open sourced, written in Swift and not a wrapper over compiled lib
• Description does not say "written in Swift" or variant 🤓