[gdk-pixbuf] doc: Update supported options

[Bastien Nocera <hadess src gnome org>]

commit c4a5f4889ce44877f5b5c104ce828219cc6baf95
Author: Bastien Nocera <hadess hadess net>
Date:   Tue Oct 21 18:24:44 2014 +0200

    doc: Update supported options
    
    Document the "multipage" option added in commit
    09b3fc03284ac4f9a4f466ba908f9cd7309b2ced

 gdk-pixbuf/gdk-pixbuf.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)
---
diff --git a/gdk-pixbuf/gdk-pixbuf.c b/gdk-pixbuf/gdk-pixbuf.c
index 6552521..6ea8a1b 100644
--- a/gdk-pixbuf/gdk-pixbuf.c
+++ b/gdk-pixbuf/gdk-pixbuf.c
@@ -897,7 +897,8 @@ gdk_pixbuf_fill (GdkPixbuf *pixbuf,
  * options for cursor definitions. The PNG loader provides the tEXt ancillary
  * chunk key/value pairs as options. Since 2.12, the TIFF and JPEG loaders
  * return an "orientation" option string that corresponds to the embedded 
- * TIFF/Exif orientation tag (if present).
+ * TIFF/Exif orientation tag (if present). Since 2.32, the TIFF loader sets
+ * the "multipage" option string to "yes" when a multi-page TIFF is loaded.
  * 
  * Return value: the value associated with @key. This is a nul-terminated 
  * string that should not be freed or %NULL if @key was not found.