Mention deprecated package rdf-js

[tpluscode]

I have just deprecated the package rdj-js on NPM. It was high time, now that I recently also removed all of its usages from DefinitelyTyped (DefinitelyTyped/DefinitelyTyped#68132, DefinitelyTyped/DefinitelyTyped#68159)

I mention it alongside @types/rdf-js in the readme

[changeset-bot]

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Latest commit: 0e47e71

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