Fixed minor typos in the docs examples.
Fixed minor typos in the docs examples.

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