Improve docfx_project/examples/index.md

[Bagisislam]

using var browserFetcher = new BrowserFetcher();
await browserFetcher.DownloadAsync();
var browser = await Puppeteer.LaunchAsync(new LaunchOptions
{
Headless = true
});
var page = await browser.NewPageAsync();
await page.GoToAsync("http://www.google.com");
await page.ScreenshotAsync(outputFile);

I attempted to run that code in .net 8.0 but i couldn't so I mean that
that library works and I can not achieve to run it or the doc and examples are not enough to explain to the library or the library and examples is not working.( And or, I also might be not smart to run that code or understand the library.)