Adding dsl usage to readme

Author: mcgin

README.md

@@ -4,3 +4,11 @@ bitbucket-plugin
 [![Build Status](https://jenkins.ci.cloudbees.com/job/plugins/job/bitbucket-plugin/badge/icon)](https://jenkins.ci.cloudbees.com/job/plugins/job/bitbucket-plugin/)
 
 See details on [wiki](https://wiki.jenkins-ci.org/display/JENKINS/BitBucket+Plugin)
+
+# Job DSL
+The plugin supports the following dsl extension to enable bitbucket pushes to trigger a build:
+```freeStyleJob('test-job') {
+  triggers{
+    bitbucketPush()
+  }
+}```