fix time estimation for exercises

SarahAlidoost · SarahAlidoost · commit 1afa69f57131 · 2020-09-04T15:19:07.000+02:00
diff --git a/_episodes/02-installation.md b/_episodes/02-installation.md
@@ -1,7 +1,7 @@
 ---
 title: "Installation"
 teaching: 10
-exercises: 20
+exercises: 10
 questions:
 - "What are the prerequisites for installing ESMValTool?"
 - "How do I confirm that the installation was successful?"
