Up docs (#1910)

* Up docs

This gave me a real headache. On some html documents / pages pdf would be generated prematurely with no text.
Relates to puppeteer/puppeteer#422

* Update README.md

* Update README.md

README.md

@@ -89,7 +89,8 @@ using var browserFetcher = new BrowserFetcher();
 await browserFetcher.DownloadAsync();
 await using var browser = await Puppeteer.LaunchAsync(new LaunchOptions {Headless = true});
 await using var page = await browser.NewPageAsync();
-await page.GoToAsync("http://www.google.com");
+await page.GoToAsync("http://www.google.com"); // In case of fonts being loaded from a CDN, use WaitUntilNavigation.Networkidle0 as a second param.
+await page.EvaluateExpressionHandleAsync("document.fonts.ready"); // Wait for fonts to be loaded. Omitting this might result in no text rendered in pdf.
 await page.PdfAsync(outputFile);
 ```
 <sup><a href='/lib/PuppeteerSharp.Tests/PageTests/PdfTests.cs#L29-L38' title='Snippet source file'>snippet source</a> | <a href='#snippet-pdfasync' title='Start of snippet'>anchor</a></sup>