Show markdown reference for the description block

https://ombulabs.atlassian.net/browse/DT-264

**Branch/Commit:**

Main branch.

**Describe the feature:**

> **As a \**
> **I want to see a quick reference of some markdown syntax**
> **So I don't have to look for that in other places**

I imagine a small `(?)` element next to the description that, on hover, shows a quick cheat-sheet of the basic for formatting and code blocks.

**Problem:**

Currently, if you need some syntax reference, you have to google for it or remember it. Also, for example, 4-space indentation looks better than tripple backtick for code blocks, maybe we can suggest to use the former instead in that cheat-sheet.

**Resources:**

Here in github, we have this legend below the description block, clicking it takes you to a documentation page, we could also do that, linking to this same documtation maybe if we don't want a custom cheat-sheet.


**I will abide by the [code of conduct](CODE_OF_CONDUCT.md)**

L’issue identifie le bloc de description comme point d’entrée, mais ne nomme aucun fichier ni test. Commencez par localiser cette UI et vérifier comment son contenu Markdown est actuellement rendu ; comparez la référence au survol proposée avec la légende ou la documentation GitHub liée. Le travail est terminé lorsque les utilisateurs peuvent accéder à une référence Markdown de base et concise sans quitter le flux de description.

Rédigé par le modèle d'indexation à partir du texte de l'issue.