Added Community Curated Kotlin Resources

[rohduggal]

https://hackr.io/tutorials/learn-kotlin

• Project Name:
• Project URL:
• Project Description:
• Why it should be added to awesome-kotlin:
• At least 8 stars (GitHub project)
• Updated contents.json instead of README
• Lib is fully open sourced, written in Kotlin and not a wrapper over compiled lib
• Description does not say "written in Kotlin" or variant 🤓