[gnome-boxes.wiki] Change page slug for "Building instructions"

[Felipe Borges <felipeborges src gnome org>]

commit c80cba93e4d5665fb2ef39878f581687455c0eaf
Author: Felipe Borges <felipeborges gnome org>
Date:   Tue Mar 19 13:40:39 2019 +0000

    Change page slug for "Building instructions"

 GNOME-Boxes:-Developer-guide.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/GNOME-Boxes:-Developer-guide.md b/GNOME-Boxes:-Developer-guide.md
index a193080..6834d67 100644
--- a/GNOME-Boxes:-Developer-guide.md
+++ b/GNOME-Boxes:-Developer-guide.md
@@ -4,7 +4,7 @@ Welcome to the **GNOME Boxes Developer guide**! This wiki is focused on develope
 
 This guide intends to provide information to help new contributors and also serve as a reference for 
experienced contributors.
 
-### [Building instructions](building-boxes)
+### [Building instructions](building)
 
 How to build GNOME Boxes in a Flatpak container or in your host operating system.