improve readability jenkins redis

Change-Id: I27460d069e0f6242aa346f7a59b0c19912f26e21
Reviewed-on: https://gerrit.instructure.com/c/canvas-lms/+/274118
Reviewed-by: Aaron Ogata <aogata@instructure.com>
Tested-by: Aaron Ogata <aogata@instructure.com>
Tested-by: Service Cloud Jenkins <svc.cloudjenkins@instructure.com>
QA-Review: Aaron Ogata <aogata@instructure.com>
Product-Review: Aaron Ogata <aogata@instructure.com>

Jenkinsfile.redis

@@ -36,6 +36,7 @@ pipeline {
         }
       }
     }
+
     stage('Pull Redis Image') {
       steps {
         script {
@@ -43,6 +44,7 @@ pipeline {
         }
       }
     }
+
     stage('Tag Redis Image') {
       steps {
         script {