Mercure extension for ddev

This extension is based on dunglas/mercures implementation.

To install it, run ddev get Rindula/ddev-mercure.

The mercurehost will be available under mercure.${DDEV_HOSTNAME}. So for example.ddev.site the url will be mercure.example.ddev.site. From inside the web container, you can reach mercure under http://mercure:3000.