Update extension: md to adoc for kotlin, java-springboot, groovy
Update extension: md to adoc for kotlin, java-springboot, groovy

confluentinc/examples,confluentinc/examples,confluentinc/examples,confluentinc/examples,confluentinc/examples,confluentinc/examples,confluentinc/examples,confluentinc/examples,confluentinc/examples,confluentinc/examples