Add contact field to erc.yml

[nuest]

We could add our own contact field, besides the human-readable information in the metadata, readme, main document etc.

It would allow to cover some specific aspects of research publications, research software, and data:

• use ORCID-URL instead of Email (Emails change with people changing institutes, happens regularly in academia), even instead of person name
• add an expiration date for contacts, effectively "this is how long my contract/the project is running and that is how long I expect to be able to answer your questions on this piece of research", or even "this is how long I expect to be interested in this topic"
• could even add support pricing or expected answering time

This is a really good idea. I remember, we had this in mind for quite a while.