add Jenkinsfile for php image

dockerfiles/tasks/php/Jenkinsfile

@@ -0,0 +1,13 @@
+pipeline {
+    agent any
+    triggers {
+        cron('@daily')
+    }
+    stages {
+        stage('Build Image') {
+            steps {
+                build job: '_build_image', parameters: [string(name: 'IMAGE', value: 'php')], quietPeriod: 1
+            }
+        }
+    }
+}