Adding start and end date attribute to relationships

This was written 2 years ago about this topic:

This might be a better explanation for what I mean:
A BB edition is NOT the same as a book edition.

Many of the editions I added look like the example in the linked thread.

[first known] release date: 1983

Annotations:

Confirmed editions [editions that are just reprints]:
3. edition: 1983
5. edition 1986

So the publishing date for this BB edition is not just 1983

We can do it this way, but it’s far from perfect I think