docs+README: improve documentation

Change-Id: I562508869f7e60ccf465b8c1acdf63e27c905c7a
diff --git a/docs/SECURITY-CONFIG.rst b/docs/SECURITY-CONFIG.rst
index 7ee9d81..769696c 100644
--- a/docs/SECURITY-CONFIG.rst
+++ b/docs/SECURITY-CONFIG.rst
@@ -37,6 +37,11 @@
 
 Users should create keys according to the naming and signing hierarchies above.
 
+
+.. note::
+
+    Detailed information about key setup is given in NLSR Developer's Guide.
+
 Certificate Publishing
 ----------------------