feat: implement livebook for exercises

[SadeQL]

This PR changes several stuff:

• Rename Level to Section to avoid some misunderstandings (like need to finish level 1, which is beginner level before jumping into the next level).
• Implement 2 exercises on Livebook for the first section. This needs to be discussed and enriched in a near future.

The livebook password is written directly on the md file. Is it necessary to have a .env for that, since everything should be public?

The cons of that is everyone having access of the livebook can edit everything.

[scollon42]

I think it would make more sense to host some .livemd files in the repository and then to offer the possibility to open it with liveview (with this feature : https://livebook.dev/badge).

We would need to make the repository public, but in my opinion, it would make sense (event without communicating on it)

[SadeQL]

Yeah good idea. I'll check how that works. For now the badge only generates a button that redirects to the livebook.

[scollon42]

Yeah good idea. I'll check how that works. For now the badge only generates a button that redirects to the livebook.

Yeah, but It allow you to choose between running it locally (and provide detailled steps to install livebook) or to run it with fly.io 👍

[SadeQL]

Yeah good idea. I'll check how that works. For now the badge only generates a button that redirects to the livebook.

Yeah, but It allow you to choose between running it locally (and provide detailled steps to install livebook) or to run it with fly.io 👍

True! I changed it to a badge. It might be interesting to take a moment during backend chapters to talk about relevant exercises to put in this learning path.

[scollon42]

Great! Can you also add the code from your livebook into your PR ? (in a livemd file ?)

[SadeQL]

Great! Can you also add the code from your livebook into your PR ? (in a livemd file ?)

Done! It's within a exercises folder as there are 3 sections. I think it'd be clearer organizing this way.