feat: Add module pureconfig with tests and basic documentation

[jakubjanecek]

feat: Add module example to show how to use the code

build: Tweak the build so that it all works together well

[augi]

It's not clear to me why I should use this module instead of using pureconfig directly. Could you please describe the reasons in the README? Possibly also show an example how the module simplifies the usage etc.
Thanks!

[jakubjanecek]

@augi This module is very simple so the benefit is not substantial. It gives you 3 things: wrapping in Sync, improved error message and conventional (according to this project) way of doing things. Of course you can use pureconfig directly, nothing against that, but you will have to write Sync[Task].delay repeatedly and you might want to wrap this functionality into some class which is basically what this module is doing.

I will write some documentation covering the design of this project but not as part of this PR. Alright?