Update description on `other` slot

[anitacaron]

Currently, the description says it is pipe-separated, but to be quickly loaded into JSON, this slot should be a JSON-looking string, for example {"key": "value"}.

[anitacaron]

It has been discussed to change this slot to be modelled as a dict, but also, there's a possibility to leave it as it's because it's already been used in other ways.