More readable README

[DvaMishkiLapa]

No matter how many READMEs I write, I always end up with a book about technical details.

Here's something that would probably improve the situation:

• We need to think about how we can merge the support tables for different OSes (after PR Adding Linux support #24);
• It might be worth making some .md documents:
  • Main (header, general description, support info, links to other documents, acknowledgements);
  • For building;
  • Configuration descriptions.

We need to quickly explain to the user the basics of how to run Client and Server. VPK installation is unlikely to be a problem, people will mostly come via VitaDB. They will get the client files from the repository page, as they are not in VitaDB.

[DvaMishkiLapa]

Closed in #26