entrypoint.sh CRLF ending problem

Hello. Slidev project is really cool and I am appropriate for this.

I found that the container is not working properly because of crlf ending of `entrypoint.sh`.

I could manage it by simply changing it to lf ending.

I don't know whether it's because of GitHub commit policy, but I think it would be really helpful if we add some troubleshootings in README.md.

Thank you very much.
