Change Jenkins section to CI/CD

CI/CD will include Jenkins and other CI/CD systems.

In addition, added a couple of questions on various topics.

exercises/cicd/solutions/remove_builds_solution.groovy

@@ -0,0 +1,16 @@
+def removeOldBuilds(buildDirectory, days = 14) {
+
+  def wp = new File("${buildDirectory}")
+  def currentTime = new Date()
+  def backTime = currentTime - days
+
+  wp.list().each { fileName ->
+      folder = new File("${buildDirectory}/${fileName}")
+      if (folder.isDirectory()) {
+          def timeStamp = new Date(folder.lastModified())
+          if (timeStamp.before(backTime)) {
+            folder.delete()
+          }
+      }
+  }
+}

exercises/cicd/solutions/remove_jobs_solution.groovy

@@ -0,0 +1,6 @@
+def jobs = Jenkins.instance.items.findAll { job -> job.name =~ /"test"/ }
+    
+jobs.each { job ->
+    println job.name
+    //job.delete()
+}