Add an example of Hello world in sbt to make it not clear to people new to sbt that the only way to define a task is in Scala. If they don't read the details they miss that point.

Detailed-Topics/Tasks.md

@@ -41,7 +41,17 @@ expression in a [[build.sbt|Getting Started Basic Def]].
 
 # Defining a New Task
 
-## Hello World example
+## Hello World example (sbt)
+
+build.sbt
+
+```scala
+
+TaskKey[Unit]("hello") := println("hello world!")
+
+```
+
+## Hello World example (scala)
 
 project/Build.scala