docs: document access.conf issue
docs: document access.conf issue

Closes #3945

dokku/dokku,claytonbrown/dokku,dokku/dokku,claytonbrown/dokku,claytonbrown/dokku,progrium/dokku,progrium/dokku,progrium/dokku,claytonbrown/dokku,progrium/dokku,progrium/dokku,claytonbrown/dokku,dokku/dokku,claytonbrown/dokku,dokku/dokku,claytonbrown/dokku,progrium/dokku,progrium/dokku,progrium/dokku,dokku/dokku,dokku/dokku,dokku/dokku,dokku/dokku,claytonbrown/dokku