[doc] Fix thal link (puppeteer#806)

This patch adds missing protocol to the link in example's README.md

examples/README.md

@@ -4,7 +4,7 @@
 
 ## Web scraping
 - [Puppetron](https://github.com/cheeaun/puppetron) - Demo site that shows how to use Puppeteer and Headless Chrome to render pages. Inspired by [GoogleChrome/rendertron](https://github.com/GoogleChrome/rendertron).
- - [Thal](medium.com/@e_mad_ehsan/getting-started-with-puppeteer-and-chrome-headless-for-web-scrapping-6bf5979dee3e) - Getting started with Puppeteer and Chrome Headless for Web Scraping.
+ - [Thal](https://medium.com/@e_mad_ehsan/getting-started-with-puppeteer-and-chrome-headless-for-web-scrapping-6bf5979dee3e "An article on medium") - Getting started with Puppeteer and Chrome Headless for Web Scraping.
 
 ## Testing
 - [angular-puppeteer-demo](https://github.com/Quramy/angular-puppeteer-demo) - Demo repository explaining how to use Puppeteer in Karma.