[tepl] metadata docs: write class description for MetadataAttic

[Sébastien Wilmet <swilmet src gnome org>]

commit 1ad814d1024c966368ec84314f53933caf12b59f
Author: Sébastien Wilmet <swilmet gnome org>
Date:   Fri May 29 23:25:31 2020 +0200

    metadata docs: write class description for MetadataAttic

 tepl/tepl-metadata-attic.c | 2 ++
 1 file changed, 2 insertions(+)
---
diff --git a/tepl/tepl-metadata-attic.c b/tepl/tepl-metadata-attic.c
index 48ed5d4..4061cbe 100644
--- a/tepl/tepl-metadata-attic.c
+++ b/tepl/tepl-metadata-attic.c
@@ -4,6 +4,8 @@
 
 #include "tepl-metadata-attic.h"
 
+/* Some metadata put into the attic. */
+
 struct _TeplMetadataAtticPrivate
 {
        /* Keys: not nullable gchar *