ms-sbvar: update documentation for final_year, final_subperiod defaults

doc/dynare.texi

@@ -6016,11 +6016,11 @@ The first period of data (@i{i.e.} for quarterly data, an integer in
 [@code{1,4}]). Default: @code{1}
 
 @item final_year = @var{INTEGER}
-The last year of data. Default: @code{none}
+The last year of data. Default: Set to encompass entire dataset
 
 @item final_subperiod = @var{INTEGER}
 The final period of data (@i{i.e.} for monthly data, an integer in
-[@code{1,12}]. Default: @code{4}
+[@code{1,12}]. Default: Set to encompass entire dataset
 
 @item datafile = @var{FILENAME}
 @xref{datafile}.