qom: Documentation addition for object_class_by_name()

Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
[AF: Document the possible NULL return value]
Signed-off-by: NAndreas Färber <afaerber@suse.de>

include/qemu/object.h

@@ -555,6 +555,12 @@ ObjectClass *object_class_dynamic_cast(ObjectClass *klass,
  */
 const char *object_class_get_name(ObjectClass *klass);
 
+/**
+ * object_class_by_name:
+ * @typename: The QOM typename to obtain the class for.
+ *
+ * Returns: The class for @typename or %NULL if not found.
+ */
 ObjectClass *object_class_by_name(const char *typename);
 
 void object_class_foreach(void (*fn)(ObjectClass *klass, void *opaque),