Add comment on targetJavaVersion.

build.gradle

@@ -7,6 +7,8 @@ archivesBaseName = project.archives_base_name
 version = project.mod_version
 group = project.maven_group
 
+// This field defines the Java version your mod target.
+// The Minecraft launcher currently installs Java 8 for users, so your mod probably wants to target Java 8 too.
 def targetJavaVersion = 8
 
 repositories {
@@ -48,7 +50,6 @@ tasks.withType(JavaCompile).configureEach {
 	// If Javadoc is generated, this must be specified in that task too.
 	it.options.encoding = "UTF-8"
 
-	// The Minecraft launcher currently installs Java 8 for users, so your mod probably wants to target Java 8 too
 	// JDK 9 introduced a new way of specifying this that will make sure no newer classes or methods are used.
 	// We'll use that if it's available, but otherwise we'll use the older option.
 	if (JavaVersion.current().isJava9Compatible()) {