Microsoft.Extensions.Configuration.Json dependency

[archerian]

Microsoft.Extensions.Configuration.Json is a required dependency for this feature, might be a good idea to add this to the documentation

[nblumhardt]

Hi! Thanks for the note. The package you mention is only required if JSON configuration is needed; this package supports the other Microsoft.Extensions.Configuration.* providers, too, e.g. including environment variables.

I'll try cleaning up the README wording 👍