[gnome-boxes] help: Fix installation of 3D acceleration page

[Felipe Borges <felipeborges src gnome org>]

commit 989cafcfe21d1798f9a85ebec8434d04b0949088
Author: Felipe Borges <felipeborges gnome org>
Date:   Wed Oct 7 11:20:07 2020 +0200

    help: Fix installation of 3D acceleration page

 help/meson.build | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/help/meson.build b/help/meson.build
index 14762958..a5d7bbc1 100644
--- a/help/meson.build
+++ b/help/meson.build
@@ -1,5 +1,5 @@
 help_files = [
-  '3d-acceleration',
+  '3d-acceleration.page',
   'backup.page',
   'create.page',
   'delete.page',