Updated Server Build level API (markdown)

Server---Build-level-API.md

@@ -13,14 +13,16 @@ val uiContext = taskKey[sbt.UIContext]("All user interaction should be driven th
 
 ```scala
 package sbt
-trait UIContext {
-
+sealed trait UIContext {
   /** Prompts the user for input, optionally with a mask for characters. */
-  def readLine(prompt: String, mask: Option[Char] = None): Option[String]
+  def readLine(prompt: String, mask: Boolean): Option[String]
+  // TODO - Ask for input with autocomplete?
 
   /** Sends an event out to all registered event listeners. */
   def sendEvent[T: Format](event: T): Unit
+  def sendGenericEvent(data: JsValue): Unit
 }
+private[sbt] abstract class AbstractUIContext extends UIContext
 ```
 
 # 3. Plugin API
@@ -29,6 +31,11 @@ trait UIContext {
 trait Plugin {
   ...
   def serializers: Seq[(AttributeKey[_], Format[_])] = Nil
+
+  // Example types for keys....
+  //  TaskKey[T] =>  AttributeKey[Task[T]] -> Format[T]
+  //  SettingKey[T] => AttributeKey[T] -> Format[T]
+  //  InputKey[T] => AttributeKey[InputTask[T]] -> Format[T]
 }
 ```