Document link to version

It is because Products and Versions are not linkable, like most other items.
This is because Product and versions are environmental data, such as resource, customer, team.
You cannot even link items to these environmental data.

When it is interesting to have some link to them, there are specific select lists, with a dedicated meaning.
- Product / Version on tickets and activities, as origin version or target version
- Resource on most items, as responsible
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