Fix tyndp rhein main link

[lindnemi]

The link was both in the NEP and in the TYNDP data, but the rule build_transmission_projects failed to recongnize it.

This PR updates both the source data, as well as the matching logic (the latter was done with ChatGPT)

Changes proposed in this Pull Request

Checklist

Required:

• Changes are tested locally and behave as expected.
• Code and workflow changes are documented.
• A release note entry is added to doc/release_notes.md.
• The description is human-written and any AI-generated content is marked.

If applicable:

• Changes in configuration options are reflected in scripts/lib/validation.
• For new data sources or versions, these instructions have been followed.
• New rules are documented in the appropriate doc/*.md files.