Allow assets to be exported with a prefix
[issue link]E.g. https://github.com/zeit/next.js/pull/2145/files?diff=split
This is useful for deployment to Github (project) pages, where projects are hosted on a relative URL, not the root
E.g. https://github.com/zeit/next.js/pull/2145/files?diff=split
This is useful for deployment to Github (project) pages, where projects are hosted on a relative URL, not the root