Include Meriam’s suggestion

Author: julienrf

_getting-started/index.md

@@ -41,7 +41,7 @@ Install it on your system with the following instructions.
 
 Along with managing JVMs, `cs setup` also installs useful command-line tools:
 
-- A JDK
+- A JDK (if you don't have one already)
 - The [sbt](https://www.scala-sbt.org/) build tool
 - [Ammonite](https://ammonite.io/), an enhanced REPL
 - [scalafmt](https://scalameta.org/scalafmt/), the Scala code formatter