docs: fix several doxygen errors

Change-Id: If86c628b2b794cba0e3697bfe1d88ce752104ce1
Refs: #3210
diff --git a/src/management/nfd-controller.hpp b/src/management/nfd-controller.hpp
index 8b08754..331810f 100644
--- a/src/management/nfd-controller.hpp
+++ b/src/management/nfd-controller.hpp
@@ -34,6 +34,7 @@
  * \defgroup management Management
  * \brief Classes and data structures to manage NDN forwarder
  */
+
 /**
  * \ingroup management
  * \brief NFD Management protocol - ControlCommand client