Duplicate items when `<registry id>` differs from directory name

[strogonoff]

For example, for this reference:

https://github.com/ietf-ribose/iana-registries/blob/main/language-tag-extensions-registry/language-tag-extensions-registry.xml

Two items are generated:

• https://github.com/ietf-tools/relaton-data-iana/blob/main/data/language-tag-extensions-registry.yaml
• https://github.com/ietf-tools/relaton-data-iana/blob/main/data/language-tag-extensions-registry_language-tag-extensions-registry-1.yaml

[ronaldtse]

This is intended. An IANA registry collection is a collection of registries, i.e. it has multiple registries.

Citations occasionally cite the full registry collection, or usually just 1 registry.

In the new setup, every individual registry is citable.