Fix snippet of code about using `cheerio` and `discoverResources` at readme
Fix snippet of code about using `cheerio` and `discoverResources` at readme

https://github.com/cgiffard/node-simplecrawler/issues/264
civalin/node-simplecrawler,simplecrawler/simplecrawler,cgiffard/node-simplecrawler,simplecrawler/simplecrawler