[gtk: 1/2] textbuffer: Add missing public API documentation.

[Matthias Clasen <matthiasc src gnome org>]

commit b2ca94793403dfb99b725809d96f2dae0c17ae63
Author: Robert Ancell <robert ancell canonical com>
Date:   Mon Jan 13 12:07:15 2020 +1300

    textbuffer: Add missing public API documentation.
    
    This API was added in a52757874ee.

 gtk/gtktextbuffer.c | 8 ++++++++
 1 file changed, 8 insertions(+)
---
diff --git a/gtk/gtktextbuffer.c b/gtk/gtktextbuffer.c
index 5ec18f7c5e..8bf2d50356 100644
--- a/gtk/gtktextbuffer.c
+++ b/gtk/gtktextbuffer.c
@@ -4077,6 +4077,14 @@ cut_or_copy (GtkTextBuffer *buffer,
     }
 }
 
+/**
+ * gtk_text_buffer_get_selection_content:
+ * @buffer: a #GtkTextBuffer
+ *
+ * Get a content provider for this buffer.
+ *
+ * Returns: (transfer full): a new #GdkContentProvider.
+ **/
 GdkContentProvider *
 gtk_text_buffer_get_selection_content (GtkTextBuffer *buffer)
 {