lokdocview: Added some missing comments/annotations

Change-Id: I2f62bae37719ce96677a5ca6ffd93c8edb325a6a
Reviewed-on: https://gerrit.libreoffice.org/20777Reviewed-by: David Tardon <dtardon@redhat.com>
Tested-by: David Tardon <dtardon@redhat.com>

include/LibreOfficeKit/LibreOfficeKitGtk.h

@@ -123,12 +123,17 @@ float                          lok_doc_view_get_zoom               (LOKDocView*
 /**
  * lok_doc_view_get_parts:
  * @pDocView: The #LOKDocView instance
+ *
+ * Returns: Part refers to either individual sheets in a Calc, or slides in Impress,
+ * and has no relevance for Writer.
  */
 int                            lok_doc_view_get_parts              (LOKDocView* pDocView);
 
 /**
  * lok_doc_view_get_part:
  * @pDocView: The #LOKDocView instance
+ *
+ * Returns: Current part number of the document
  */
 int                            lok_doc_view_get_part               (LOKDocView* pDocView);
 
@@ -144,6 +149,8 @@ void                           lok_doc_view_set_part               (LOKDocView*
  * lok_doc_view_get_part_name:
  * @pDocView: The #LOKDocView instance
  * @nPart:
+ *
+ * Returns: Get current part name of loaded document
  */
 char*                          lok_doc_view_get_part_name          (LOKDocView* pDocView,
                                                                     int nPart);