Add URL configuration to Docker images

You can now configure the Docker image for the ValidMind documentation site to meet your specific needs. This update simplifies deployment in your infrastructure by allowing you to set two parameters:

• VALIDMIND_URL: Specifies where to access the ValidMind platform.
• JUPYTERHUB_URL: Specifies where to access JupyterHub.

Set these URLs using one of the supported methods detailed in the URL configuration for Docker.