Minor doc fixes.
Minor doc fixes.

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