java_lang: add missing README.java-lang
diff --git a/java_gen/README.java-lang b/java_gen/README.java-lang
new file mode 100644
index 0000000..754c13b
--- /dev/null
+++ b/java_gen/README.java-lang
@@ -0,0 +1 @@
+Work in progress to port OpenFlow/J to support OpenFlow 1.0, 1.1., 1.2, and 1.3.