Include overriding the ref macro in the v1.5 migration guide (#5319)

[Preview](https://docs-getdbt-com-git-dbeatty10-patch-3-dbt-labs.vercel.app/docs/dbt-versions/core-upgrade/upgrading-to-v1.5)

## What are you changing in this pull request and why?

resolves #5053

Starting in v1.5, users will need to update overrides of the `ref` macro
in order to use [model
versions](https://docs.getdbt.com/docs/collaborate/govern/model-versions).

## Checklist
- [x] Review the [Content style
guide](https://github.com/dbt-labs/docs.getdbt.com/blob/current/contributing/content-style-guide.md)
so my content adheres to these guidelines.

website/docs/docs/dbt-versions/core-upgrade/05-upgrading-to-v1.5.md

@@ -112,6 +112,8 @@ The built-in [collect_freshness](https://github.com/dbt-labs/dbt-core/blob/1.5.l
 
 Finally: The [built-in `generate_alias_name` macro](https://github.com/dbt-labs/dbt-core/blob/1.5.latest/core/dbt/include/global_project/macros/get_custom_name/get_custom_alias.sql) now includes logic to handle versioned models. If your project has reimplemented the `generate_alias_name` macro with custom logic, and you want to start using [model versions](/docs/collaborate/govern/model-versions), you will need to update the logic in your macro. Note that, while this is **not** a prerequisite for upgrading to v1.5—only for using the new feature—we recommmend that you do this during your upgrade, whether you're planning to use model versions tomorrow or far in the future.
 
+Likewise, if your project has reimplemented the `ref` macro with custom logic, you will need to update the logic in your macro as described [here](https://docs.getdbt.com/reference/dbt-jinja-functions/builtins).
+
 ### For consumers of dbt artifacts (metadata)
 
 The [manifest](/reference/artifacts/manifest-json) schema version will be updated to `v9`. Specific changes: