graph: doc review

src/entt/graph/adjacency_matrix.hpp

@@ -13,11 +13,7 @@
 
 namespace entt {
 
-/**
- * @cond TURN_OFF_DOXYGEN
- * Internal details not to be documented.
- */
-
+/*! @cond TURN_OFF_DOXYGEN */
 namespace internal {
 
 template<typename It>
@@ -88,11 +84,7 @@ template<typename Container>
 }
 
 } // namespace internal
-
-/**
- * Internal details not to be documented.
- * @endcond
- */
+/*! @endcond */
 
 /**
  * @brief Basic implementation of a directed adjacency matrix.