[libshumate] demos: Build docs in the demo Flatpak

[Marcus Lundblad <mlundblad src gnome org>]

commit 556bacee05638cde845d715079dafe62614a5c18
Author: James Westman <james jwestman net>
Date:   Tue Feb 16 23:57:24 2021 -0600

    demos: Build docs in the demo Flatpak
    
    This makes it easier to test docs changes locally.

 demos/org.gnome.Shumate.Demo.json | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
---
diff --git a/demos/org.gnome.Shumate.Demo.json b/demos/org.gnome.Shumate.Demo.json
index 7d54d90..ed91a4b 100644
--- a/demos/org.gnome.Shumate.Demo.json
+++ b/demos/org.gnome.Shumate.Demo.json
@@ -32,7 +32,8 @@
             "name" : "libshumate",
             "buildsystem" : "meson",
             "config-opts" : [
-                "-Ddemos=true"
+                "-Ddemos=true",
+                "-Dgtk_doc=true"
             ],
             "builddir" : true,
             "sources" : [