Fix broken DaC doc structure

[AntoineThebaud]

With the latest release of Perses that added a lot of docs for the Dashboard-as-Code part, our current way to publish the docs to https://perses.dev actually didnt work well:

From this base structure..

..everything was flattened and grouped inside the same folder:

On top of this, most if not all the links between those docs are broken.

I suppose that the fix consists mostly in making this part of the synchronization script more complex to handle more than 1 level of depth https://github.com/perses/website/blob/main/scripts/synchronize.sh#L126.

[AntoineThebaud]

@nicolastakashi any chance that you have a quickwin solution here? 😄

[Nexucis]

fix with the new website