[gtk-web/gtk4-prep: 2/3] installation: Update linux versions

[Matthias Clasen <matthiasc src gnome org>]

commit b44d25d95ef57eba5877291b29a445a388c67cad
Author: Matthias Clasen <mclasen redhat com>
Date:   Mon Oct 5 22:17:21 2020 -0400

    installation: Update linux versions
    
    Point to 3.99 as the current version, move 3.24 to
    the list of 3.x versions, and drop all the others.
    Stop mentioning GTK 1 and 2 altogether.
    
    Links here will need updating when 4.0 is released.

 _docs/installations/linux.md | 39 ++++++++-------------------------------
 1 file changed, 8 insertions(+), 31 deletions(-)
---
diff --git a/_docs/installations/linux.md b/_docs/installations/linux.md
index df8d005a..1b6f9b15 100644
--- a/_docs/installations/linux.md
+++ b/_docs/installations/linux.md
@@ -16,7 +16,7 @@ To build an environment for GTK, install all the dependencies listed below:
 
 Dependency | Source
 --- | :---:
-GTK | [<i class="fas fa-download"></i>](https://download.gnome.org/sources/gtk+/3.24/)
+GTK | [<i class="fas fa-download"></i>](https://download.gnome.org/sources/gtk+/3.99/)
 GLib | [<i class="fas fa-download"></i>](https://download.gnome.org/sources/glib/)
 Pango | [<i class="fas fa-download"></i>](https://download.gnome.org/sources/pango/)
 Gdk-pixbuf | [<i class="fas fa-download"></i>](https://download.gnome.org/sources/gdk-pixbuf/)
@@ -24,10 +24,10 @@ ATK | [<i class="fas fa-download"></i>](https://download.gnome.org/sources/atk/)
 GObject-Introspection | [<i class="fas 
fa-download"></i>](https://download.gnome.org/sources/gobject-introspection/)
 Epoxy | [<i class="fas fa-download"></i>](https://download.gnome.org/sources/libepoxy/)
 
-The current stable API version of GTK3 is 3.24.
+The current unstable API version of GTK is 3.99.
 
-To build GTK, see the [installation guide](https://developer.gnome.org/gtk3/stable/gtk-building.html).
-For additional help, the [frequently asked questions 
page](https://developer.gnome.org/gtk3/stable/gtk-question-index.html) is a
+To build GTK, see the [installation guide](https://developer.gnome.org/gtk4/unstable/gtk-building.html).
+For additional help, the [frequently asked questions 
page](https://developer.gnome.org/gtk4/unstable/gtk-question-index.html) is a
 good starting point.
 
 ## Development version
@@ -38,35 +38,12 @@ download, and optionally build, all the required project dependencies.
 
 ## Older Versions
 
-Some applications still require GTK 2, an older stable version of GTK. You
-can have the run-time and development environments for GTK 3.x, GTK 2.x and
-GTK 1.2 installed simultaneously on your computer.
+Some applications still require GTK 3, an older stable version of GTK. You
+can have the run-time and development environments for GTK 4.x and GTK 3.x
+installed simultaneously on your computer.
 
 ### GTK v3.x
 
 Version | Packages
 --- | ---
-GTK 3.22 | [Sources](https://download.gnome.org/sources/gtk+/3.22/)
-GTK 3.20 | [Sources](https://download.gnome.org/sources/gtk+/3.20/)
-GTK 3.18 | [Sources](https://download.gnome.org/sources/gtk+/3.18/)
-GTK 3.16 | [Sources](https://download.gnome.org/sources/gtk+/3.16/)
-GTK 3.14 | [Sources](https://download.gnome.org/sources/gtk+/3.14/)
-GTK 3.12 | [Sources](https://download.gnome.org/sources/gtk+/3.12/)
-GTK 3.10 | [Sources](https://download.gnome.org/sources/gtk+/3.10/)
-GTK 3.8 | [Sources](https://download.gnome.org/sources/gtk+/3.8/)
-GTK 3.6 | [Sources](https://download.gnome.org/sources/gtk+/3.6/)
-GTK 3.4 | [Sources](https://download.gnome.org/sources/gtk+/3.4/)
-GTK 3.2 | [Sources](https://download.gnome.org/sources/gtk+/3.2/)
-GTK 3.0 | [Sources](https://download.gnome.org/sources/gtk+/3.0/)
-
-### GTK v2.x
-
-Version | Packages
---- | ---
-GTK 2.24 | [Sources](https://download.gnome.org/sources/gtk+/2.24/)
-
-### GTK v1.x
-
-Version | Packages
---- | ---
-GTK 1.2 | [Sources](https://download.gnome.org/sources/gtk+/1.2/)
+GTK 3.24 | [Sources](https://download.gnome.org/sources/gtk+/3.24/)