Inform user about data usage

[csarven]

When dokieli creates some information based on a user action, e.g., notification, annotation, feed, it would typically try to include some data about the signed-in user, e.g., their URI, name, email.

For certain features/actions, there should be an indicator to inform the user about what data would be included. There can also be settings to allow / disallow certain information.

Related:

• If built-in proxy is used, inform user #241