Improved: clarify use of sourceSets in build.gradle

Mentions the difference and reason of it for build.gradle sourceSets.
Under main are the integration tests, under tst are the unit tests

build.gradle

@@ -240,6 +240,7 @@ def excludedJavaSources = [
 ]
 
 sourceSets {
+ // This is for integration tests (DB access)
  main {
  java {
  srcDirs = getDirectoryInActiveComponentsIfExists('src/main/java')
@@ -254,7 +255,7 @@ sourceSets {
  srcDirs += getDirectoryInActiveComponentsIfExists('dtd')
  }
  }
- // This is unit tests. Integration tests must be above because of compilation issues.
+ // This is for unit tests (no DB access)
  test {
  java {
  srcDirs = getDirectoryInActiveComponentsIfExists('src/test/java')