Code organisation (Update contributing.md accordingly)

[TheCodeArtist]

Creating this issue to discuss the layout of code in this repo.

Current plan is to have this repo as a showcase of various features/demos.

• App.js - the landing page shall be the menu / ToC / list of demos.

Is it possible to have each demo (and its related resources) saved within its own sub-directory within src/

TODO:

• Update Contributing.md with agreed-upon convention to add new features/demos.
• Highlight this in README.md

[huiyie]

Thanks for creating this issue, definitely will need this to scale this project up and add more features 👍