docs: Update of tutorials and other minor fixes

Change-Id: I87d8679d38b3f17f8d4d8dbad3d5f01b3cc4ce7b
diff --git a/docs/examples.rst b/docs/examples.rst
index 793cd89..7e901ec 100644
--- a/docs/examples.rst
+++ b/docs/examples.rst
@@ -1,6 +1,12 @@
 Trivial applications
 ====================
 
+.. note::
+
+    To successfully run the following examples, please make sure that NFD is properly
+    configured and running.  For more information about NFD, refer to `NFD's official
+    homepage <http://named-data.net/doc/NFD/>`_.
+
 Trivial consumer
 ----------------