Update so-features-enable

salt/common/tools/sbin/so-features-enable

@@ -17,6 +17,28 @@
 . /usr/sbin/so-common
 local_salt_dir=/opt/so/saltstack/local
 
+cat << EOF
+This program will switch from the open source version of the Elastic Stack to the Features version licensed under the Elastic license.
+If you proceed, then we will download new Docker images and restart services.
+
+Please review the Elastic license:
+https://raw.githubusercontent.com/elastic/elasticsearch/master/licenses/ELASTIC-LICENSE.txt
+
+Please also note that, if you have a distributed deployment and continue with this change, Elastic traffic between nodes will change from encrypted to cleartext!
+(We expect to support Elastic Features Security at some point in the future.)
+
+Do you agree to the terms of the Elastic license and understand the note about encryption?
+
+If so, type AGREE to accept the Elastic license and continue.  Otherwise, just press Enter to exit this program without making any changes.
+EOF
+
+read INPUT
+if [ "$INPUT" != "AGREE" ]; then
+        exit
+fi
+
+echo "Please wait while switching to Elastic Features."
+
 manager_check() {
   # Check to see if this is a manager
   MANAGERCHECK=$(cat /etc/salt/grains | grep role | awk '{print $2}')