Update readme

README.md

@@ -4,8 +4,49 @@
 
 Provides a Gradle DSL for dynamically generating Buildkite pipelines.
 
+## Usage
+
+First add the plugin to your project:
+
 ```groovy
 plugins {
-    id 'widen.buildkite' version '0.1.2'
+    id 'widen.buildkite' version '0.1.3'
+}
+```
+
+Now you can start defining Buildkite pipelines using Groovy inside your `build.gradle`. Below is an example of defining a Gradle task `deployStagePipeline`:
+
+```groovy
+tasks.create('deployStagePipeline', com.widen.plugins.UploadPipeline) {
+    def regions = ['us-east-1', 'eu-west-1']
+
+    regions.each { region ->
+        commandStep {
+            label ":rocket: Deploy app to stage $region"
+            command "./bksh deploy-helm-2 -r app-stage -f app-stage-${region}.yaml -g \${DOCKER_TAG} -k ${k8s('stage', region)} -v 4.2.3"
+            agentQueue 'deploy-stage', region
+        }
+        commandStep {
+            label ":sleeping: Wait for stage $region deploy to finish"
+            command "./bksh wait-for-deploy http://app.${region}.widen-stage.com/health"
+            agentQueue 'deploy-stage', region
+        }
+    }
+
+    waitStep()
+
+    regions.each { region ->
+        commandStep {
+            label ":smoking: Integration test the stage $region deployment"
+            command "./gradlew app-app:integrationTest -Dapp.endpoint=http://app.${region}.widen-stage.com --continue \${GRADLE_SWITCHES}"
+            branch 'master'
+            agentQueue 'integ-stage', region
+            dockerComposeContainer 'gradle'
+        }
+    }
 }
 ```
+
+This example demonstrates the power of using a language like Groovy to dynamically generate a pipeline based on lists or other dynamic code. You could even parallelize your unit tests by generating a separate step for each subproject reported by Gradle!
+
+Running this Gradle task locally spits out the JSON representation, so you can see if your pipeline looks correct. Inside Buildkite the pipeline will be added to the current build.