message: Clarify how to configure catalog rules in threat model
  The threat model previously told users to configure `catalog.rules` or `catalog.locations[].rules`, but didn't provide any help as to how those needed to be configured.  Updated this to point directly to documentation on how to configure the rules.
diff: @@ -54,7 +54,7 @@ Backstage also supports authentication through a proxy where the user identity i
  ## Catalog
  -Integrators should configure `catalog.rules` and `catalog.locations[].rules` to limit the allowed entity kinds that users can define. In general it is best to restrict definition of User, Group, and Template entities so that internal users cannot register additional ones. Template entities define actions that are executed on the backend hosts, and while the goal is for these actions to be secure regardless of input, it is still a more sensitive context and it is recommended that you protect it with additional checks. It is very important to not allow registration of User and Group entities if you ingest and rely on these as organizational data in your catalog. Doing so could otherwise open up for the ability to impersonate users and confuse group membership information. You should always ingest organizational data using a statically configured catalog location or an entity provider reading from a trusted source. The entities emitted directly by an entity provider are always trusted and rules are not applied to them, but any entities produced further down the chain are still subject to the rules.
  +Integrators should configure [catalog rules](https://backstage.io/docs/features/software-catalog/configuration#catalog-rules) to limit the allowed entity kinds that users can define. In general it is best to restrict definition of User, Group, and Template entities so that internal users cannot register additional ones. Template entities define actions that are executed on the backend hosts, and while the goal is for these actions to be secure regardless of input, it is still a more sensitive context and it is recommended that you protect it with additional checks. It is very important to not allow registration of User and Group entities if you ingest and rely on these as organizational data in your catalog. Doing so could otherwise open up for the ability to impersonate users and confuse group membership information. You should always ingest organizational data using a statically configured catalog location or an entity provider reading from a trusted source. The entities emitted directly by an entity provider are always trusted and rules are not applied to them, but any entities produced further down the chain are still subject to the rules.
  The Catalog does not aim to protect against resource exhaustion attacks in its default setup. If you need to prevent your internal users from being able to register large amounts of entities, then it is recommended to disable entity registration and use a different approach for discovering entities. One way to mitigate any resource exhaustion attacks is to only allow the catalog to read from trusted SCM sources that have an audit trail. Catalog currently lacks limits for entity hierarchy depth and entity size, which we hope to address in the future.
  