Edit README.md for second exercise

Author: eloots

exercises/exercise_001_getting_started/README.md

@@ -6,7 +6,12 @@ At this stage, we have a single Scala 3 source file in
 the `src/main/scala` folder.
 
 We can run it in different ways, one of which is utilising
-`scala-cli.
+`scala-cli`:
+
+```
+$ scala-cli run src/main/scala/Hello.scala
+```
+
 
 TODO: set-up information about dev environment (JDK and scala-cli)