Add contributing guidelines (#350)
Add contributing guidelines (#350)

* Create CONTRIBUTING.md

* Rename CONTRIBUTING.md to .github/CONTRIBUTING.md

* Rename .github/CONTRIBUTING.md to CONTRIBUTING.md

Triple-T/gradle-play-publisher,MaTriXy/gradle-play-publisher-1,MaTriXy/gradle-play-publisher-1,Triple-T/gradle-play-publisher,Triple-T/gradle-play-publisher,MaTriXy/gradle-play-publisher-1