tests: adds a comment to the setup.yml playbook for clarification

Signed-off-by: Andrew Schoen <aschoen@redhat.com>

tests/functional/setup.yml

@@ -14,6 +14,8 @@
       set_fact:
         is_atomic: '{{ stat_ostree.stat.exists }}'
 
+      # we need to install this so the Socket testinfra module
+      # can use netcat for testing
     - name: install net-tools
       package:
         name: net-tools