Fix docs for hide_gridlines().
Fix docs for hide_gridlines().

Closes #129.

yaojingwu1992/XlsxWriter,liukaijv/XlsxWriter,liukaijv/XlsxWriter,seize-the-dave/XlsxWriter,liukaijv/XlsxWriter,jvrsantacruz/XlsxWriter,gechong/XlsxWriter,Thhhza/XlsxWriter,applicationdevm/XlsxWriter,yaojingwu1992/XlsxWriter,liukaijv/XlsxWriter,jvrsantacruz/XlsxWriter,gechong/XlsxWriter,applicationdevm/XlsxWriter,Thhhza/XlsxWriter,jkyeung/XlsxWriter,jkyeung/XlsxWriter,Thhhza/XlsxWriter,jmcnamara/XlsxWriter,jmcnamara/XlsxWriter,jmcnamara/XlsxWriter,yaojingwu1992/XlsxWriter,jvrsantacruz/XlsxWriter,gechong/XlsxWriter,jkyeung/XlsxWriter,jmcnamara/XlsxWriter,seize-the-dave/XlsxWriter,mdeemer/XlsxWriter,applicationdevm/XlsxWriter,mdeemer/XlsxWriter,seize-the-dave/XlsxWriter,gechong/XlsxWriter,jvrsantacruz/XlsxWriter,yaojingwu1992/XlsxWriter,mdeemer/XlsxWriter,Thhhza/XlsxWriter,mdeemer/XlsxWriter,jkyeung/XlsxWriter,seize-the-dave/XlsxWriter,applicationdevm/XlsxWriter