Add documentation of JDK 9 module name.
diff --git a/README.md b/README.md
index 07a2ddb..1f6f7b9 100644
--- a/README.md
+++ b/README.md
@@ -10,3 +10,8 @@
and [JAX-WS](https://github.com/javaee/jax-ws-spec) for data content handling.
JAF is included in Java SE 6 and later.
+
+This standalone release of JAF uses a
+[Java Platform Module System](http://openjdk.java.net/projects/jigsaw/spec/)
+"automatic" module name of `java.activation`, to match the module name
+used in JDK 9. A future version will include full module metadata.
