Update README.md

[sander-bol]

It looks like this project has been moved into an organisation, but some of the references in the README are still pointing to Andreas' own fork. Everything still works because Github aliased it, but seems nicer to be consistent.

All Submissions:

• Have you followed the guidelines in our Contributing document?
• Have you checked to ensure there aren't other open Pull Requests for the same update/change?

New Feature Submissions:

1. Does your submission pass tests?
2. Have you lint your code locally prior to submission?

Changes to Core Features:

• Have you added an explanation of what your changes do and why you'd like us to include them?
• [-] Have you written new tests for your core changes, as applicable?
• [-] Have you successfully ran tests with your changes locally?

[icanhazstring]

Thanks for the adjustments 👍