Fix broken link on RLMObject

[lukluca]

Updates a link to an external resource that was returning a 404 error, replacing it with a new, valid URL. This ensures users can access the necessary resource without interruption.

This fix the issue #8795

[cla-bot]

Thank you for your pull request and welcome to our community. We could not parse the GitHub identity of the following contributors: Luca Tagliabue.
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