Add README with note that the project is no longer maintained

Change-Id: I0577230108d3c17c16aa197f1d706a6cfc056849

README

diff --git a/README b/README
new file mode 100644
index 0000000..010216c
--- /dev/null
+++ b/README
@@ -0,0 +1,3 @@
+NOTE: This project is not actively maintained. If you are interested in using
+it, or if you want to volunteer to take over as maintainer, contact
+repo-discuss@googlegroups.com.