Improve existing introduction for novice users

[alexgarel]

As someone who is not an experimented developers (innovator, scientists, junior programmer) I come to the API documentation

I want to :

• have an introduction that explain me what is an API
• links me to useful definitions and tutorials (eg: https://developer.mozilla.org/en-US/docs/Glossary/API)
• eventually add a use case to explain why I would use it

[pratik9315]

Hey! I saw that this issue is open. Im new here and this seems like a perfect issue to start with! Can I work on this if its okay with everyone?

[alexgarel]

@pratik2315 yes, go :-)