Update man page

data/yad.1

@@ -965,14 +965,21 @@ is a name of mime type (for example text/plain). This option may be used multipl
 .B \-\-image-filter=\fI[NAME]\fP
 Add filter for images supported by gdk-pixbuf library. \fINAME\fP in as optional name for this filter.
 .TP
+This options applies to all of yad's file chooser dialogs.
+
+.SS File preview options
+.TP
 .B \-\-add-preview
 Add preview widget. Preview images loads from normal (default) or large thumbnails according to XDG Thumbnails
 specification v0.8.0 (http://standards.freedesktop.org/thumbnail-spec/latest/) or creates by yad for image files and saves
 as normal or large thumbnails.
-.TP \--large-preview
+.TP 
+.B \-\-large-preview
 Use large previews by default. This option can be permanently turned on through yad settings.
-
+.TP
 This options applies to all of yad's file chooser dialogs.
+.TP
+\fBNOTE:\fP YAD doesn't check mtime for thumbnailed images and doesn't updates preview if origial file was changed after thumbnail was created.
 
 .SS Miscellaneous options
 .TP