Fix : full description on participatory space show page

[Stef-Rousset]

🎩 Description
The aim of this PR is to have the description visible when arriving on the show page of a participatory space.

Testing

1. As an admin, go to a process or an assembly, and add a long description text (>300)
2. As a user in the FO go to the show page of this participatory space, and see that the description is fully visible (cf screenshot)
3. Click on the "show less" btn and see that the description is truncated.
4. Click on the "More information" btn and see that the description is fully visible

📌 Related Issues
Fixes https://github.com/OpenSourcePolitics/release-party-0.31/issues/33

Tasks

• Add specs

📷 Screenshots