Feature Request: Support individual metadata property pages under /submission_metadata

[alexskr]

We recently added a new API endpoint: /submission_metadata
This provides a list of metadata property descriptions (e.g., versionIRI, version, etc.).

Issue:
Currently, the endpoint returns a single page listing all metadata properties. Attempting to access a specific property like
/submission_metadata/version results in a "page not found" error.

Proposal:
Enable direct access to individual metadata properties via their attribute URIs. For example:

GET /submission_metadata/version

GET /submission_metadata/versionIRI

This would allow us to send direct links to specific metadata definitions and improve documentation clarity.