[General][Fundamental] Basics of using container environment

[bharatk-parallel]

The feature request is to make the users of this repository to get familiar with the concepts of :
-- Virtual Environments
-- Types of Virtual Env: Conda, Containers ( Docker, Singularity ), VM
-- Container usage: How to use containers like Singularity and Docker

The fundamentals here will help developers using this repository to get familiar with containers and how to use them in their own environment.