[easytag] Add a comment to clarify ID3 APIC descriptions

[David King <davidk src gnome org>]

commit 8a96195566b8a03de9c2b3fa82a27ceeeba6e6a6
Author: David King <amigadave amigadave com>
Date:   Thu Nov 10 16:28:35 2016 +0000

    Add a comment to clarify ID3 APIC descriptions

 src/tags/id3v24_tag.c |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)
---
diff --git a/src/tags/id3v24_tag.c b/src/tags/id3v24_tag.c
index b73e946..43700f6 100644
--- a/src/tags/id3v24_tag.c
+++ b/src/tags/id3v24_tag.c
@@ -501,7 +501,9 @@ id3tag_read_file_tag (GFile *gfile,
             }
         }
 
-        /* Picture description. */
+        /* Picture description. The accepted fields are restricted to those
+         * of string type, as the description field is the only one of string
+         * type in the APIC tag (the MIME type is Latin1 type). */
         update |= libid3tag_Get_Frame_Str (frame, EASYTAG_ID3_FIELD_STRING,
                                            &description);