[gtk+] Document gtk_builder_extend_wth_template

[Matthias Clasen <matthiasc src gnome org>]

commit f0a74bc302ab76028c334893f78a0c7af25ffecc
Author: Matthias Clasen <mclasen redhat com>
Date:   Sun Nov 8 18:40:35 2015 -0500

    Document gtk_builder_extend_wth_template

 docs/reference/gtk/gtk3-sections.txt |    1 +
 gtk/gtkbuilder.c                     |   15 ++++++++++++++-
 2 files changed, 15 insertions(+), 1 deletions(-)
---
diff --git a/docs/reference/gtk/gtk3-sections.txt b/docs/reference/gtk/gtk3-sections.txt
index 858c0c7..e8ad757 100644
--- a/docs/reference/gtk/gtk3-sections.txt
+++ b/docs/reference/gtk/gtk3-sections.txt
@@ -628,6 +628,7 @@ gtk_builder_add_from_string
 gtk_builder_add_objects_from_file
 gtk_builder_add_objects_from_string
 gtk_builder_add_objects_from_resource
+gtk_builder_extend_with_template
 gtk_builder_get_object
 gtk_builder_get_objects
 gtk_builder_expose_object
diff --git a/gtk/gtkbuilder.c b/gtk/gtkbuilder.c
index 07e0bb2..c074eb5 100644
--- a/gtk/gtkbuilder.c
+++ b/gtk/gtkbuilder.c
@@ -1110,10 +1110,23 @@ gtk_builder_add_objects_from_file (GtkBuilder   *builder,
   return 1;
 }
 
-/* Main private entry point for building composite container
+
+/**
+ * gtk_builder_extend_with_template:
+ * @builder: a #GtkBuilder
+ * @widget: the widget that is being extended
+ * @template_type: the type that the template is for
+ * @buffer: the string to parse
+ * @length: the length of @buffer (may be -1 if @buffer is nul-terminated)
+ * @error: (allow-none): return location for an error, or %NULL
+ *
+ * Main private entry point for building composite container
  * components from template XML.
+ *
  * This is exported purely to let gtk-builder-tool validate
  * templates, applications have no need to call this function.
+ *
+ * Returns: A positive value on success, 0 if an error occurred
  */
 guint
 gtk_builder_extend_with_template (GtkBuilder   *builder,