[gnome-todo] doc: fix build file

[Georges Basile Stavracas Neto <gbsneto src gnome org>]

commit 0bdd9922d6829bb8da8168d2b2fad59eca550080
Author: Georges Basile Stavracas Neto <georges stavracas gmail com>
Date:   Thu Sep 28 09:58:59 2017 -0300

    doc: fix build file
    
    It was missing a comma, and breaking the build with
    --enable-gtk-doc

 doc/reference/meson.build |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/doc/reference/meson.build b/doc/reference/meson.build
index 1e59f14..46b1f76 100644
--- a/doc/reference/meson.build
+++ b/doc/reference/meson.build
@@ -58,7 +58,7 @@ gnome.gtkdoc(
           mkdb_args: [ '--sgml-mode', '--output-format=xml' ],
         html_assets: html_images,
             install: true,
-        install_dir: doc_path
+        install_dir: doc_path,
   gobject_typesfile: meson.project_name() + '.types',
           scan_args: [
     '--rebuild-types',