message: updated writeFile props
diff: /*
  * NAME: demo.js
  * AUTH: Brent Ely (https://github.com/gitbrent/)
  - * DATE: 20210403
  + * DATE: 20210502
  * DESC: PptxGenJS feature demos for Node.js
  * REQS: npm 4.x + `npm install pptxgenjs`
  *
  @@ -45,7 +45,7 @@ if (process.argv.length > 2) {
  slide.addShape(pptx.shapes.OVAL_CALLOUT, { x: 6, y: 2, w: 3, h: 2, fill: "00FF00", line: "000000", lineSize: 1 }); // Test shapes availablity
  // EXAMPLE 1: Saves output file to the local directory where this process is running
  - pptx.writeFile(exportName)
  + pptx.writeFile({ fileName: exportName })
  .catch((err) => {
  throw new Error(err);
  })
  