[gnome-builder] doc: add TOC for extending application menus

[Christian Hergert <chergert src gnome org>]

commit 5272f9a08d96e0cd282c462b115b6303f7f71fac
Author: Christian Hergert <chergert redhat com>
Date:   Tue Mar 7 14:24:43 2017 -0800

    doc: add TOC for extending application menus

 doc/plugins/index.rst |    1 +
 doc/plugins/menus.rst |    5 +++++
 2 files changed, 6 insertions(+), 0 deletions(-)
---
diff --git a/doc/plugins/index.rst b/doc/plugins/index.rst
index 11d5d6a..295cf56 100644
--- a/doc/plugins/index.rst
+++ b/doc/plugins/index.rst
@@ -19,6 +19,7 @@ Creating Plugins
    keybindings
    langserv
    search
+   menus
    preferences
    transfers
    workers
diff --git a/doc/plugins/menus.rst b/doc/plugins/menus.rst
new file mode 100644
index 0000000..9487a51
--- /dev/null
+++ b/doc/plugins/menus.rst
@@ -0,0 +1,5 @@
+###########################
+Extending Application Menus
+###########################
+
+