Allow replacing medium.com links with Scribe

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Scribe is an alternative open-source, self-hostable front-end to medium that works without javascript.

Project page: https://sr.ht/~edwardloveall/scribe/

List of instances: https://git.sr.ht/~edwardloveall/scribe/tree/HEAD/docs/instances.md

Please allow replacing medium.com links with Scribe and add an option in settings that allows specifying the Scribe instance (similar to what Nitter already does for Youtube/Intagram etc.)