[gtk/filename-sorter] stringsorter: Add more detail to the docs

[Matthias Clasen <matthiasc src gnome org>]

commit 05323869d72e466faa286881c959c1de58cfe22b
Author: Matthias Clasen <mclasen redhat com>
Date:   Tue Oct 11 14:03:57 2022 -0400

    stringsorter: Add more detail to the docs
    
    Mention when a collation value of NONE might
    be useful.

 gtk/gtkstringsorter.c | 6 ++++++
 1 file changed, 6 insertions(+)
---
diff --git a/gtk/gtkstringsorter.c b/gtk/gtkstringsorter.c
index 266fc81e55..507adca17c 100644
--- a/gtk/gtkstringsorter.c
+++ b/gtk/gtkstringsorter.c
@@ -335,6 +335,12 @@ gtk_string_sorter_class_init (GtkStringSorterClass *class)
    *
    * The collation method to use for sorting.
    *
+   * The `GTK_COLLATION_NONE` value is useful when the expression already
+   * returns collation keys, or strings that need to be compared byte-by-byte.
+   *
+   * The default value, `GTK_COLLATION_UNICODE`, compares strings according
+   * to the [Unicode collation algorithm](https://www.unicode.org/reports/tr10/).
+   *
    * Since: 4.10
    */
   properties[PROP_COLLATION] =