message: Update documentation of readonly mode to clarify what functionality is disallowed
diff: @@ -106,8 +106,7 @@ with [Static Location Configuration](#static-location-configuration) or a
  discovery processor like
  [GitHub Discovery](../../integrations/github/discovery.md). To enforce usage of
  processors to locate entities we can configure the catalog into `readonly` mode.
  -This configuration disables the mutating backend catalog APIs and disallows
  -users from registering new entities at run-time.
  +This configuration disables registering and deleting locations with the catalog APIs.
  ```yaml
  catalog:
  @@ -117,6 +116,8 @@ catalog:
  > **Note that any plugin relying on the catalog API for creating, updating and
  > deleting entities will not work in this mode.**
  +Deleting an entity by UUID, `DELETE /entities/by-uid/:uid`, is allowed when using this mode. It may be rediscovered as noted in [explicit deletion](life-of-an-entity.md#explicit-deletion).
  +
  A common use case for this configuration is when organizations have a remote
  source that should be mirrored into Backstage. To make Backstage a mirror of
  this remote source, users cannot also register new entities with e.g. the
  