[gtk: 17/19] windows: Update the docs for env vars

[Matthias Clasen <matthiasc src gnome org>]

commit 58e65ae7ddd55915782f7278955ad5c3073489c6
Author: Matthias Clasen <mclasen redhat com>
Date:   Fri Jul 16 08:27:54 2021 -0400

    windows: Update the docs for env vars
    
    We've replaced some env vars with a new one.
    Update the docs to match.

 docs/reference/gtk/windows.md | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)
---
diff --git a/docs/reference/gtk/windows.md b/docs/reference/gtk/windows.md
index 886b99f42f..96fa5e6291 100644
--- a/docs/reference/gtk/windows.md
+++ b/docs/reference/gtk/windows.md
@@ -14,14 +14,19 @@ instructions, binary downloads, etc, can be found
 The Win32 GDK backend can be influenced with some additional environment
 variables.
 
-### GDK_IGNORE_WINTAB
+### GDK_WIN32_TABLET_INPUT_API
 
-If this variable is set, GTK doesn't use the Wintab API for tablet support.
+If this variable is set, it determines the API that GTK uses for tablet support.
+The possible values are:
 
-### GDK_USE_WINTAB
+`none`
+: Disables tablet support
 
-If this variable is set, GTK uses the Wintab API for tablet support.
-This is the default.
+`wintab`
+: Use the Wintab API
+
+`winpointer`
+: Use the Windows Pointer Input Stack API. This is the default.
 
 ## Windows-specific handling of cursors