Add README about the origin of linkdiscovery
diff --git a/src/main/java/net/onrc/onos/ofcontroller/linkdiscovery/README b/src/main/java/net/onrc/onos/ofcontroller/linkdiscovery/README
new file mode 100644
index 0000000..3cec58d
--- /dev/null
+++ b/src/main/java/net/onrc/onos/ofcontroller/linkdiscovery/README
@@ -0,0 +1,8 @@
+Note about this directory
+=========================
+
+This directory contains link discovery manager and it's related module derived from Flood Light v0.9.0.
+Many of the code is unmodified from it's original state, but they had to be moved due to package visibility etc.
+
+Compare with floodlight's linkdiscovery directory to see what was modified from it's original code.
+