update README.md for the migration from jade to pug
update README.md for the migration from jade to pug

There were breaks between the transition from jade to pug (https://pugjs.org/api/migration-v2.html). Some of the links in the readme point to an old documentation or old converter. I've updated all this.
vymarkov/hackathon-starter,niallobrien/hackathon-starter-plus,sahat/hackathon-starter,sahat/hackathon-starter,sahat/hackathon-starter,niallobrien/hackathon-starter-plus,peterblazejewicz/hackathon-starter,peterblazejewicz/hackathon-starter,vymarkov/hackathon-starter,peterblazejewicz/hackathon-starter