docs: Change documentation to consistenly use "Returns:"

Instead "Return value:" or "Return:"

gtk/gtkgesturepan.c

@@ -299,7 +299,7 @@ gtk_gesture_pan_new (GtkWidget      *widget,
  *
  * Returns the orientation of the pan gestures that this @gesture expects.
  *
- * Return value: the expected orientation for pan gestures
+ * Returns: the expected orientation for pan gestures
  *
  * Since: 3.14
  */

gtk/gtkoverlay.c

@@ -576,7 +576,7 @@ gtk_overlay_class_init (GtkOverlayClass *klass)
    * #GtkScrolledWindow, the overlays are placed relative
    * to its contents.
    *
-   * Return: %TRUE if the @allocation has been filled
+   * Returns: %TRUE if the @allocation has been filled
    */
   signals[GET_CHILD_POSITION] =
     g_signal_new (I_("get-child-position"),

modules/printbackends/cloudprint/gtkcloudprintaccount.c

@@ -97,7 +97,7 @@ gtk_cloudprint_account_get_type (void)
  * Creates a new #GtkCloudprintAccount object, representing a Google
  * Cloud Print account and its state data.
  *
- * Return value: the new #GtkCloudprintAccount object
+ * Returns: the new #GtkCloudprintAccount object
  **/
 GtkCloudprintAccount *
 gtk_cloudprint_account_new (const gchar *id,

modules/printbackends/cloudprint/gtkprintbackendcloudprint.c

@@ -163,7 +163,7 @@ gtk_print_backend_cloudprint_get_type (void)
  * object. #GtkPrintBackendCloudprint implements the #GtkPrintBackend
  * interface using REST API calls to the Google Cloud Print service.
  *
- * Return value: the new #GtkPrintBackendCloudprint object
+ * Returns: the new #GtkPrintBackendCloudprint object
  **/
 GtkPrintBackend *
 gtk_print_backend_cloudprint_new (void)

modules/printbackends/cloudprint/gtkprintercloudprint.c

@@ -102,7 +102,7 @@ gtk_printer_cloudprint_get_type (void)
  * implements the #GtkPrinter interface and stores a reference to the
  * #GtkCloudprintAccount object and the printer-id to use
  *
- * Return value: the new #GtkPrinterCloudprint object
+ * Returns: the new #GtkPrinterCloudprint object
  **/
 GtkPrinterCloudprint *
 gtk_printer_cloudprint_new (const char *name,