fix: DomCorpus warning

Author: vinniefalco

include/mrdox/Metadata/DomMetadata.hpp

@@ -40,13 +40,15 @@ class MRDOX_DECL
     Corpus const& corpus;
 
     /** Destructor.
-
-        Ownership of the corpus is not released.
     */
-    ~DomCorpus();
+    virtual ~DomCorpus();
 
     /** Constructor.
 
+        Ownership of the specified Corpus is not
+        transferred; the caller is responsible for
+        ensuring the lifetime extension of the object.
+
         @param corpus The Corpus whose metadata to use.
     */
     explicit