Update setup.md

point out this is optional

Author: hschellman

setup.md

@@ -1,7 +1,7 @@
 ---
 title: Mission Setup
-teaching: 60
-exercises: 20
+teaching: 1
+exercises: 1
 questions:
 - How do I prepare for the DUNE computing tutorial?
 objectives:  
@@ -33,6 +33,9 @@ You should join the DUNE Slack instance and look in #computing-training-basics (
 
 Windows users are invited to review the [Windows Setup page]({{ site.baseurl }}/Windows.html).
 
+
+#  If you are already set up to run DUNE code you can skip all of this. It is a placeholder for other tutorials. 
+
 ## Step 1: DUNE membership
 
 To follow most of this training, you must be on the DUNE Collaboration member list. If you are not, talk to your supervisor or representative to get on it.