[gtk/docs-gtk-org] Hide the GDK_DEPRECATED_IN_* symbols

[Emmanuele Bassi <ebassi src gnome org>]

commit da96f491d3a3cf68a86685113c57f94a0e8739bc
Author: Emmanuele Bassi <ebassi gnome org>
Date:   Mon Aug 2 18:46:14 2021 +0100

    Hide the GDK_DEPRECATED_IN_* symbols
    
    We don't need them in the public API reference.

 gtk3/gdk/gdk3.toml.in | 4 ++++
 1 file changed, 4 insertions(+)
---
diff --git a/gtk3/gdk/gdk3.toml.in b/gtk3/gdk/gdk3.toml.in
index 394a6c26e9..f25cfc2165 100644
--- a/gtk3/gdk/gdk3.toml.in
+++ b/gtk3/gdk/gdk3.toml.in
@@ -44,3 +44,7 @@ content_images = [
   "gtk-logo.svg",
 ]
 urlmap_file = "urlmap.js"
+
+[[object]]
+pattern = "DEPRECATED_IN_3_*"
+hidden = true