[gtk-web] Update reference links

[Emmanuele Bassi <ebassi src gnome org>]

commit 63195b3a0719300c900f2f9affb736f293c5c5d2
Author: Emmanuele Bassi <ebassi gmail com>
Date:   Wed Jan 6 16:32:07 2021 +0000

    Update reference links
    
    We need to specify the versions.
    
    Fixes: #70

 _docs/apis/index.md | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)
---
diff --git a/_docs/apis/index.md b/_docs/apis/index.md
index eda21834..e270997c 100644
--- a/_docs/apis/index.md
+++ b/_docs/apis/index.md
@@ -6,12 +6,12 @@ application development.
 
 ### User interface and display
 
- - [GTK](https://developer.gnome.org/gtk/unstable/) — Widget toolkit for graphical interfaces
- - [GDK](https://developer.gnome.org/gdk/unstable/) — Low-level abstraction for the windowing system
- - [GSK](https://developer.gnome.org/gsk/unstable/) — Low-level scene graph and 3D rendering API
+ - [GTK](https://developer.gnome.org/gtk4/unstable/) — Widget toolkit for graphical interfaces
+ - [GDK](https://developer.gnome.org/gdk4/unstable/) — Low-level abstraction for the windowing system
+ - [GSK](https://developer.gnome.org/gsk4/unstable/) — Low-level scene graph and 3D rendering API
  - [Cairo](https://developer.gnome.org/cairo/stable/) — 2D, vector-based drawing for high-quality graphics
  - [Pango](https://developer.gnome.org/pango/stable/) — International text rendering with full Unicode 
support
- - [ATK](https://developer.gnome.org/atk/stable/) — Accessibility toolkit to implement support for screen 
readers and other tools
+ - [ATK](https://developer.gnome.org/atk/stable/) — Accessibility toolkit to implement support for screen 
readers and other tools (GTK3 only)
 
 ### Storage of the user's data