Mark as inactive

README.txt

diff --git a/README.txt b/README.txt
index b5f33bb..9eca7e9 100644
--- a/README.txt
+++ b/README.txt
@@ -1,3 +1,6 @@
+This repository is no longer active - Emscripten is now based
+on the upstream llvm WebAssembly backend
+
 //===----------------------------------------------------------------------===//
 // C Language Family Front-end
 //===----------------------------------------------------------------------===//