Update Readme and Sample hocon for new settings

[to11mtm]

We don't have documentation around how to use BackwardsCompatibleSurrogatedFormatter, let alone in a way useful to users (If they REALLY want to for some reason, they'll probably have to override a serializerID or similar.

Also we should provide some docs and explanation around:

• LZ4 Settings
• converters vs converters-override
  • May be worth providing an example of how to 'override' TypelessFormatter while safely respecting Akka surrogates, etc.

[to11mtm]

Actually TBH I think the docs could use a good bit of love in general.

This shouldn't be hard, the library is simple, but we should try to give some good information to make people understand options.