Offline build broken since 2.1.0

[camillemndn]

Hi, since version 2.1.0, and more particularly #2249, offline build fail because the external dependencies are fetched at build time. Would there be a way to fix the offline build functionality? Thank you.

[jayhesselberth]

Starting from a clean site and cache, you only need to build the site once (really just pkgdown::init_site()) while online, and then dependencies will be cached for future offline builds (until you run pkgdown::clean_cache())

The only way we could get offline to work independent of connectivity is to offer an alternative way to link to CDN, which is the issue #2249 fixed.