[gtk+] Visual Studio builds: Mention about Vulkan builds

[Chun-wei Fan <fanchunwei src gnome org>]

commit cf8c72b431493203fafa0ba88ec65e7971fa12cb
Author: Chun-wei Fan <fanchunwei src gnome org>
Date:   Fri Dec 30 14:52:00 2016 +0800

    Visual Studio builds: Mention about Vulkan builds
    
    Let people know what is needed for Vulkan builds.

 build/win32/vs12/README.txt |    8 ++++++++
 1 files changed, 8 insertions(+), 0 deletions(-)
---
diff --git a/build/win32/vs12/README.txt b/build/win32/vs12/README.txt
index 2abcd66..58cd187 100644
--- a/build/win32/vs12/README.txt
+++ b/build/win32/vs12/README.txt
@@ -34,6 +34,14 @@ possible, especially those from and using the GTK+ stack (i.e. GLib,
 Cairo, ATK, Pango, GDK-Pixbuf), so that crashes caused by mixing calls
 to different CRTs can be kept at a minimum.
 
+To build with Vulkan renderer support, use the configs that end with _Vulkan.
+You will need the LunarG Vulkan SDK installed, and its include\ directory
+and Bin\ (64-bit) or Bin32 (32-bit) need to be in your INCLUDE and LIB paths
+(or need to be set in your additional include paths and additional library paths)
+so that they can be found by the build.  To run with the Vulkan renderer, set
+GSK_RENDERER=vulkan--you will need a video adapter with driver support for Vulkan
+to support this.
+
 zlib, libpng, and Cairo do contain support for compiling under VS12
 using VS project files and/or makefiles at this time of writing, For the
 GTK+ stack, VS12 project files are either available under