added warning about installing and ensure can only install workstation on centos

salt/workstation/xwindows.sls

@@ -1,3 +1,7 @@
+
+{# we only want this state to run it is CentOS #}
+{% if grains.os == 'CentOS' %}
+
 include:
   - workstation.packages
 
@@ -9,3 +13,11 @@ graphical_target:
     - require:
       - pkg: X Window System
       - pkg: graphical_extras
+
+{% else %}
+
+workstation_xwindows_os_fail:
+  test.fail_without_changes:
+    - comment: 'SO Analyst Workstation can only be installed on CentOS'
+
+{% endif %}