feat: update domain from nestrischamps.herokuapp.com to nestrischamps.io

[timotheeg]

There's a shiny new domain for nestrischamps: nestrischamps.io, so this PR updates the links :)

Changeset generated with

bash

git grep nestrischamps.herokuapp.com | cut -d: -f1 | sort | uniq | while read f; do sed -i '' -e s/nestrischamps.herokuapp.com/nestrischamps.io/ $f; done

[Stabyourself]

Looks good, ty!