Add Description for ECS Framework

[hasanbayatme]

Hi.

Thanks for your awesome work.

I have checked your Readme file but you don't provided any description about ECS framework.

ECS is Entity-component-System framework, i know how this works but a beginner or someone that doesn't knows what is the ECS framework might leave your work as an incomplete work and don't rate it or use it.

So it is good idea to provide very simple description about ECS and add a Read more link to Wikipedia articles; https://en.wikipedia.org/wiki/Entity%E2%80%93component%E2%80%93system

Thanks.