Update for latest toolchain.

Author: billabt

README.md

@@ -12,7 +12,8 @@ This package is functionally complete and has all current relevant tests passing
 
 ### Swift
 * Swift Open Source `swift-DEVELOPMENT-SNAPSHOT-2016-05-09-a` toolchain (**Minimum REQUIRED for latest release**)
-* Swift Open Source `swift-DEVELOPMENT-SNAPSHOT-2016-05-31-a` toolchain (*Recommended*)
+* Swift Open Source `swift-DEVELOPMENT-SNAPSHOT-2016-05-31-a` toolchain *or*
+* Swift Open Source `swift-DEVELOPMENT-SNAPSHOT-2016-06-06-a` toolchain (*Recommended*)
 
 ### OS X