Add requirements section to the README for apple engine.

Jeff Verkoeyen · Jeff Verkoeyen · commit b4231cf2a393 · 2016-08-24T12:53:55.000-04:00
diff --git a/README.md b/README.md
@@ -5,6 +5,13 @@
 
 An API diff tool for Objective-C, Swift, and Android code that outputs markdown.
 
+## Requirements
+
+Engine for apple APIs requires:
+
+- Xcode 8 beta 6
+- [sourcekitten](https://github.com/jpsim/SourceKitten)
+
 ## Usage
 
 Run `apidiff` from within a git repository like so:
