docs: fix capitalization in doxygen comments

Change-Id: Ibf5ee5119d12d60d382b0acef8dfd08277c18fcb
diff --git a/daemon/rib/readvertise/readvertised-route.hpp b/daemon/rib/readvertise/readvertised-route.hpp
index e4be12c..a57fe70 100644
--- a/daemon/rib/readvertise/readvertised-route.hpp
+++ b/daemon/rib/readvertise/readvertised-route.hpp
@@ -33,7 +33,7 @@
 
 namespace nfd::rib {
 
-/** \brief state of a readvertised route
+/** \brief State of a readvertised route.
  */
 class ReadvertisedRoute : noncopyable
 {