docs(api.md): fix return values of page.add*Tag() (#1269)
docs(api.md): fix return values of page.add*Tag() (#1269)


puppeteer/puppeteer,GoogleChrome/puppeteer,GoogleChrome/puppeteer,puppeteer/puppeteer,puppeteer/puppeteer,brutalcrozt/puppeteer,brutalcrozt/puppeteer,GoogleChrome/puppeteer,puppeteer/puppeteer