configuration.md shows an incorrect config for deploying keycloak

Motivation

The docs in docs/configuration.md are incorrect and do not reflect the actual schema required to deploy keycloak. Since these docs are made available to big bang consumers to help with configuration, they should be reviewed in their entirety for accuracy and updated.

Acceptance Criteria

• The configuration.md document has been updated to reflect proper process for configuring keycloak
• Once an MR is opened, reviewers must run through the document as though they are setting up keycloak for the first time and verify the procedures are accurate.