Update README.MD

[skjerns]

I've just read that visbrain is no longer maintained (which I have understanding for, I know how time consuming maintenance can be).

Would it be possible to update the README to reflect these changes? Additionally, it might be an idea to either archive the project and/or to redirect to https://github.com/x64-bit/sleep-scoring which seems to contain an updated version

Additionally, all links to visbrain.org should be removed, as it redirects to a scam site. Could change the links to https://cognitive-neuroscience-open-tools.github.io/visbrain/

related #117

[raphaelvallat]

@EtienneCmb thoughts on the above? It's concerning that visbrain.org redirects to a scam site; I agree with @skjerns's suggestion of archiving the repo/docs and/or at minima updating the links

[EtienneCmb]

I vote for archiving the project as redirecting to the sleep scoring website only reflects the sleep module. Someone interested in opening the PR?