Documentation: Purview Root Collection Admin Object ID prerequisite is not listed on prerequisites page

### Documentation Issue

The preparation prerequisite for specifying an AAD User Object ID of a the user in your AAD tenant that should be added as collection admin to the root collection of your Purview account with "Purview Root Collection Admin Object ID" is not listed on prerequisites page of the Data Management Landing Zone. Where the user sees that only in deployment experience.

### Code of Conduct

- [X] I agree to follow this project's [Code of Conduct](https://github.com/Azure/data-management-zone/blob/main/CODE_OF_CONDUCT.md)