Updated Server Build level API (markdown)

Server---Build-level-API.md

@@ -1,13 +1,15 @@
 The server aspects to sbt build will be exposed to build/plugin authors as follows:
 
 
-# 1.  A new key available which can be used to interact with the server:
+# 1. Build Keys
+
+A new key available which can be used to interact with the server:
 
 ```scala
 val uiContext = taskKey[sbt.UIContext]("All user interaction should be driven through this interface.")
 ```
 
-# 2. A new interface:
+# 2. A UI interface
 
 ```scala
 package sbt
@@ -21,10 +23,11 @@ trait UIContext {
 }
 ```
 
-# 3. An addition to plugin API:
+# 3. Plugin API
 
 ```scala
 trait Plugin {
+  ...
   def serializers: Seq[(AttributeKey[_], Format[_])] = Nil
 }
 ```