Add custom details to my profile

example use-case:
> As a member of the Translation Group on Loomio
> I want to share my contact details in an obvious place
> So members can easily establish direct communication outside of Loomio

---

Not yet sure if this should be at the level of a user profile or group membership.

Clarifying questions:

• who should be able to see these details ?
• do users need these details to be different across different groups ?

---

trello card : https://trello.com/c/TycS5zmt