Update example according to changes in jobdsl

To be in line with demos/jobs sample

Author: yogeek

Diff for: docs/seed-jobs.md

@@ -15,7 +15,7 @@ configuration-as-code file:
 jenkins:
   systemMessage: "Simple seed job example"
 jobs:
-  - >
+  - script: >
       multibranchPipelineJob('configuration-as-code') {
           branchSources {
               git {
@@ -28,4 +28,4 @@ jobs:
 
 ## Examples
 
-Please refer to [demos](../demos/jobs) for examples to configure more complex jobs.
+Please refer to [demos](../demos/jobs) for examples to configure more complex jobs.