Add guest blog post admonition, and call to action

content/blog/2017/08/2017-08-07-intro-to-plugin-development.adoc

@@ -6,6 +6,14 @@ tags:
 author: markewaite
 ---
 
+[NOTE]
+====
+This is a guest post by link:https://github.com/markewaite[Mark Waite], who maintains
+the link:https://plugins.jenkins.io/git[git plugin],
+the link:https://plugins.jenkins.io/git-client[git client plugin],
+and is a technical evangelist for link:http://cloudbees.com[CloudBees, Inc.]
+====
+
 While developing the "link:https://www.cloudbees.com/intro-plugin-development-workshop[Intro to Plugin Development]"
 workshop for Jenkins World 2017, I was impressed by the many Jenkins plugin development videos, tutorials, and guides.
 Here are some of my favorite plugin development topics and links.
@@ -65,3 +73,13 @@ Many of the Jenkins plugin development topics have dedicated pages of their own,
 === Actions
 
 * Jenkins link:https://www.cloudbees.com/blog/jenkins-internal-action-and-its-subtypes[Action and its subtypes]
+
+[WARNING]
+--
+Mark will be presenting
+link:https://www.cloudbees.com/intro-plugin-development-workshop[Intro to Plugin Development]
+at
+link:https://www.cloudbees.com/jenkinsworld/home[Jenkins World] in August.
+Register with the code `JWFOSS` for a 30% discount off your pass.
+--
+