Add missing OEO entity description to reworked OEO IRI page

[jh-RLI]

Description of the issue

The IRI pages serve as lookup page for all entities of the OEO. Since we migrated form our custom integration to the TSS Widgets we currently only show the EntityInformationWidget which does not show the entity definition.

Ideas of solution

Add the entityDescription widget alongsisde the entityInformation widget.

Workflow checklist

• I am aware of the workflow in
  CONTRIBUTING.md