[Enhancement] Add text descriptions to proposals/history

The History page in its current form is very good (I don't remember seeing it when I used the dApp the first time). I totally understand why I would need to go back in time to understand what was voted in my absence.

However, for less technical people, I think having the opportunity to add short descriptions of every past action would be nice: "deposit X amount of token", "send X money to Alex", "place X into Youves vault"…. I would argue that these messages do not need to be stored on the blockchain (and actually probably shouldn't, for privacy reasons).

Start at the History page implementation and the code that renders proposal or past-action entries. Determine how short descriptions could be added and displayed without storing them on the blockchain, as the issue requests. Done means past actions have useful user-facing descriptions while preserving the existing History view.

Written by the indexing model from the issue text.