Add info / link to attribution information for datasets

[pieper]

As @fedorov and I discussed on Slack, much of the data from TCIA / IDC requests citations if you publish it but these can be hard to find. Andrey was able to use Big Query to find the collection using the series UID, so we should enable this automatically so that users can correctly cite the sources.

[fedorov]

We have DOI for each instance in the cohort manifest, but it makes a lot of sense and is indeed important to acknowledge contributors more prominently, when the data is visualized.