Data Science flow: add small high level diagram in wiki of this project.

[ybressler]

Data Science flow: add small high level diagram in wiki of this project.

[rashnil-git]

@ybressler : Can you please add some documentation on the following:

1. Model Selection criteria and techniques
2. Feature Selection Criteria and techniques
3. Performance Metrics
4. Model workflow and life cycle diagram.

[rashnil-git]

Please use the wiki of this project : https://github.com/checkifcovid/data-science-experiments/wiki

Create different pages on this home page (one created as TODO).