Update CONTRIBUTING.md to help developers to launch the project in local machine

[jabalde]

As a developer
I want to tell other developers how they can launch the project locally
so they can contribute to the project

**

Acceptance criteria

• Include CONTRIBUTING section into README.md file
• Include styles page in CONTRIBUTING.md
• Include subsections in CONTRIBUTING.md between "Best Practices" and "Pull Request Process"
  • Dependencies
  • Build
  • Usage (only npm start and reference to README.md for options)

[adantoscano]

Hi @jabalde,
What do you mean about styles page?