Currently, when users encounter a 404 error in the default RHDH setup (e.g., after deploying with no custom configuration), the page is not helpful and does not guide users on how to resolve the issue. This can cause confusion, especially for users who may not realize that additional configuration is required to enable a functional setup.

The goal is to enhance the 404 page with a more informative message and actionable steps that guide users toward setting up their configuration properly.

Acceptance Criteria:

Add a friendly and informative message to the 404 page, including:
An explanation of why the 404 might occur (e.g., "No custom configuration provided").
A link to the documentation for creating a custom configuration file.
A reminder that the Helm chart can automatically handle baseUrl settings if used.