Step by step guide for absolute beginners to contribute

## Step by step guide for absolute beginners to contribute.
As a beginner,
I need a complete beginner's guide on how to proceed on my first issue,
so that I can break the hesitation that the beginners have which makes them reluctant to contribute.

## Required items:
1. A BEGINNER_GUIDE.md file with step by step guide.
2. How to choose the first issue and get it assigned.
3. Step by step git commands for setting repository locally.
4. Creating a pull request.
5. Relevant links to documentation.
6. What to do if get stuck.

## Definition of Done
- [ ] All of the required items are completed.
- [ ] Approval by 1 mentor.

## Estimation
12 hours