Move share link from nginx.conf to nginxconfig.txt (#395)

* ✨ feat: external shared link

* ✅

 chore: apply eslint

* Update src/nginxconfig/generators/index.js

Co-authored-by: Matt Cowley <me@mattcowley.co.uk>

* Update src/nginxconfig/generators/conf/nginx.conf.js

Co-authored-by: Matt Cowley <me@mattcowley.co.uk>

Co-authored-by: Matt Cowley <me@mattcowley.co.uk>