Update README for instructions for opting in

README.md

@@ -35,6 +35,7 @@ fct_dbt__model_executions
 fct_dbt__seed_executions
 fct_dbt__snapshot_executions
 fct_dbt__test_executions
+fct_dbt__source_executions
 ```
 
 See the generated [dbt docs site](https://brooklyn-data.github.io/dbt_artifacts/#!/overview) for documentation on each model.
@@ -73,6 +74,13 @@ packages:
     dbt run --select dbt_artifacts
     ```
 
+5. If you want to include results from the `dbt source freshness` command, you'll need to add the following flag in your `dbt_project.yml`.  This was recently added and made backwards-compatible to older core versions, so it's something that you have to opt into.
+
+    ```yml
+    flags:
+      source_freshness_run_project_hooks: true
+    ```
+
 ### Notes on upgrading
 
 Due to the structure of the project, when additional fields are added, the package needs to be re-run to ensure the tables include the new field, or it will simply error on the hook. These changes will always be implemented within a new **minor** version, so make sure that the version you use in `packages.yml` reflects this.