[goffice] Introspection fixes

[Morten Welinder <mortenw src gnome org>]

commit d1e22b125a9140b9033e30453e47d6313736007e
Author: Morten Welinder <terra gnome org>
Date:   Sat Apr 14 21:33:40 2018 -0400

    Introspection fixes

 goffice/app/go-plugin.c         |    2 +-
 goffice/graph/gog-plot-engine.c |    5 +++--
 2 files changed, 4 insertions(+), 3 deletions(-)
---
diff --git a/goffice/app/go-plugin.c b/goffice/app/go-plugin.c
index 76704a4..b7297d7 100644
--- a/goffice/app/go-plugin.c
+++ b/goffice/app/go-plugin.c
@@ -1475,7 +1475,7 @@ go_plugin_list_read_for_all_dirs (GOErrorInfo **ret_error)
 /**
  * go_plugin_db_activate_plugin_list:
  * @plugins: (element-type GOPlugin): The list of plugins
- * @ret_error: Pointer used to report errors
+ * @ret_error: (out): Pointer used to report errors
  *
  * Activates all plugins in the list. If some of the plugins cannot be
  * activated, the function reports this via @ret_error (errors don't
diff --git a/goffice/graph/gog-plot-engine.c b/goffice/graph/gog-plot-engine.c
index 488124b..3f35ab0 100644
--- a/goffice/graph/gog-plot-engine.c
+++ b/goffice/graph/gog-plot-engine.c
@@ -729,9 +729,10 @@ create_plot_families (void)
 }
 
 /**
- * gog_plot_families: (skip)
+ * gog_plot_families:
  *
- * Returns: (transfer none): the registered plot families.
+ * Returns: (transfer none) (element-type utf8 GogPlotFamily): the
+ * registered plot families.
  */
 GHashTable const *
 gog_plot_families (void)