fill in checkbox with pdf-lib

 https://github.com/Hopding/pdf-lib/issues/109

const fooCheckBox = findAcroFieldByName(pdfDoc, 'FooCheckBox');
const barCheckBox = findAcroFieldByName(pdfDoc, 'BarCheckBox');
const quxCheckBox = findAcroFieldByName(pdfDoc, 'QuxCheckBox');
const bazCheckBox = findAcroFieldByName(pdfDoc, 'BazCheckBox');

console.log('Selecting "Foo" and "Qux" boxes...');
fooCheckBox.set('V', PDFName.from('Yes'));