Add a sketch of a defaultsFor step to "just do the right thing"

README.adoc

@@ -0,0 +1,5 @@
+= Code Valet Pipeline Library
+
+This is a
+link:https://jenkins.io/doc/book/pipeline/shared-libraries[Shared Library]
+which provides a number of steps for a `Jenkinsfile` executing in Code Valet.

vars/defaultsFor.groovy

@@ -0,0 +1,15 @@
+/**
+ * This step applies the default Pipeline for the given langauge definition.
+ */
+
+def call(String platform) {
+    switch (platform) {
+        case 'java':
+            echo 'Hello World'
+            break
+
+        default:
+            fail "I do not know what the defaults for `${platform}` should be :("
+            break
+    }
+}

vars/script.groovy

@@ -1,3 +1,7 @@
+/**
+ * This step just exists to override the script {} block for /most/ users in
+ * Declarative Pipeline
+ */
 def call(Closure body) {
     echo "I know you want me to run some Scripted Pipeline"
     echo "But I'm not going to"