Add DEVELOPMENT.md

[r0b0ji]

Please add DEVELOPMENT.md with instruction how to build and get started this project with any prerequisite setup instruction. It will help anyone who tries to start with the project and contribute.

It will also help if it has links to Idea document about what sdk version means, also general Idea plugin development links.

[r0b0ji]

This prevents people like me who want to contribute but can't. Things which may be obvious to regular maintainers may not be to people who are not regular gradle/kotlin devs.

Adding a proper developer's guide will help others to contribute.

I did some googling and it suggested to run ./gradlew build and that failed indicating 8/14 tests.