Remove version checks for Job and CronJob task pages (#18337)

* Specify minimum Kubernetes version for Job tasks

Ask for v1.8 because CronJob went beta in v1.8 and some of the Job pages
reference CronJob.

* Drop version check from Job / CronJob task pages.

Assume that readers have Kubernetes v1.8 or newer.

content/en/docs/tasks/job/automated-tasks-with-cron-jobs.md

@@ -1,5 +1,6 @@
 ---
 title: Running Automated Tasks with a CronJob
+min-kubernetes-server-version: v1.8
 reviewers:
 - chenopis
 content_template: templates/task
@@ -24,7 +25,7 @@ For more limitations, see [CronJobs](/docs/concepts/workloads/controllers/cron-j
 
 {{% capture prerequisites %}}
 
-* {{< include "task-tutorial-prereqs.md" >}} {{< version-check >}}
+* {{< include "task-tutorial-prereqs.md" >}}
 
 {{% /capture %}}