Optional Admin Dashboard Deployment with SSO Integration Instructions

Note: this requires [PGO v5.1](https://www.crunchydata.com/blog/seamless-pgadmin-4-deployments-using-pgo-v5.1)

The Helm chart should not deploy the pgAdmin4 dashboard by default, but it should provide a variable to enable it and instructions for Single Sign-On (SSO) integration, so that it can be customized according to user requirements.

AC:
- [ ] Ensure that the Helm chart does not deploy the admin dashboard by default.
- [ ] Provide a configurable variable that allows users to enable or disable the admin dashboard deployment.
- [ ] Ensure the Helm chart correctly deploys the admin dashboard when the variable is set to enable it.
- [ ] Include a clear and concise guide in the documentation for users who want to enable or disable the admin dashboard.
- [ ] Provide instructions for SSO integration with the admin dashboard in the documentation.
- [ ] Test the Helm chart with various configurations to ensure compatibility and reliability of the optional admin dashboard deployment.

Start with the Helm chart and the PGO v5.1 deployment guidance linked in the issue, then review the existing documentation for dashboard configuration. Verify default, enabled, and disabled configurations, and document SSO integration. Done means the chart behaves correctly for each configuration and the guide covers optional deployment and SSO setup.

Written by the indexing model from the issue text.