Empty `remoteConfigUrl` should be the default

[bmuenzenmeyer]

Empty should be the default - pursuant to genericization of doc-kit

This is a BREAKING CHANGE for any nodejs implementation that relies on it.

Originally posted by @bmuenzenmeyer in #1005 (comment)

[bmuenzenmeyer]

relates to directly, so possibly roll into #986

[avivkeller]

@bmuenzenmeyer I'm closing in favor of #986, since the proposed solution (#1002) resolves this while resolving that