doc(app-delivery): update the documentation in the ReadMe. (#3111)

After the changes introduced with the IAction interface.

packages/@aws-cdk/app-delivery/README.md

@@ -51,7 +51,7 @@ import codebuild = require('@aws-cdk/aws-codebuild');
 import codepipeline = require('@aws-cdk/aws-codepipeline');
 import codepipeline_actions = require('@aws-cdk/aws-codepipeline-actions');
 import cdk = require('@aws-cdk/core');
-import cicd = require('@aws-cdk/cicd');
+import cicd = require('@aws-cdk/app-delivery');
 
 const app = new cdk.App();
 
@@ -101,42 +101,40 @@ pipeline.addStage({
 
 // Optionally, self-update the pipeline stack
 const selfUpdateStage = pipeline.addStage({ stageName: 'SelfUpdate' });
-new cicd.PipelineDeployStackAction(pipelineStack, 'SelfUpdatePipeline', {
-  stage: selfUpdateStage,
+selfUpdateStage.addAction(new cicd.PipelineDeployStackAction({
   stack: pipelineStack,
   input: synthesizedApp,
-});
+  adminPermissions: true,
+}));
 
 // Now add our service stacks
 const deployStage = pipeline.addStage({ stageName: 'Deploy' });
 const serviceStackA = new MyServiceStackA(app, 'ServiceStackA', { /* ... */ });
 // Add actions to deploy the stacks in the deploy stage:
-const deployServiceAAction = new cicd.PipelineDeployStackAction(pipelineStack, 'DeployServiceStackA', {
-  stage: deployStage,
+const deployServiceAAction = new cicd.PipelineDeployStackAction({
   stack: serviceStackA,
   input: synthesizedApp,
   // See the note below for details about this option.
   adminPermissions: false, 
 });
+deployStage.addAction(deployServiceAAction);
 // Add the necessary permissions for you service deploy action. This role is
 // is passed to CloudFormation and needs the permissions necessary to deploy
 // stack. Alternatively you can enable [Administrator](https://docs.aws.amazon.com/IAM/latest/UserGuide/access_policies_job-functions.html#jf_administrator) permissions above, 
 // users should understand the privileged nature of this role.
-deployServiceAAction.addToRolePolicy(
-  new iam.PolicyStatement()
-    .addAction('service:SomeAction')
-    .addResource(myResource.myResourceArn)
+deployServiceAAction.addToRolePolicy(new iam.PolicyStatement({
+    actions: ['service:SomeAction'],
+    resources: [myResource.myResourceArn],
     // add more Action(s) and/or Resource(s) here, as needed
-);
+}));
 
 const serviceStackB = new MyServiceStackB(app, 'ServiceStackB', { /* ... */ });
-new cicd.PipelineDeployStackAction(pipelineStack, 'DeployServiceStackB', {
-  stage: deployStage,
+deployStage.addAction(new cicd.PipelineDeployStackAction({
   stack: serviceStackB,
   input: synthesizedApp,
   createChangeSetRunOrder: 998,
   adminPermissions: true, // no need to modify the role with admin
-}); 
+}));
 ```
 
 #### `buildspec.yml`