URLs for vignettes linked in the readme show a security warning and are also 404 missing

[benwhalley]

This is the offending section in the readme

configr provides a more simple way to parse and generate the diverse configuration files including JSON/INI/YAML/TOML files. The configr is similar to that of package 'config'. Vignettes can be found in usage-of-configr and configuration-filetypes.