docs: adding doxygen description to ndn-l3-tracer.h
diff --git a/utils/tracers/ndn-l3-tracer.h b/utils/tracers/ndn-l3-tracer.h
index 72c4cac..625f9e1 100644
--- a/utils/tracers/ndn-l3-tracer.h
+++ b/utils/tracers/ndn-l3-tracer.h
@@ -35,6 +35,9 @@
 class Face;
 class ContentObjectHeader;
 
+/**
+ * @brief Base class for network-layer (incoming/outgoing Interests and Data) tracing of NDN stack
+ */
 class L3Tracer : public SimpleRefCount<L3Tracer>
 {
 public: