Merge pull request #8649 from nigelwright-roam/s3-discovery-docs

Added additional S3 Discovery instructions

docs/integrations/aws-s3/discovery.md

@@ -26,3 +26,16 @@ catalog:
 ```
 
 Note the `s3-discovery` type, as this is not a regular `url` processor.
+
+As this processor is not one of the default providers, you will also need to add
+the below to `packages/backend/src/plugins/catalog.ts`:
+
+```ts
+/* packages/backend/src/plugins/catalog.ts */
+
+import { AwsS3DiscoveryProcessor } from '@backstage/plugin-catalog-backend';
+
+const builder = await CatalogBuilder.create(env);
+/** ... other processors ... */
+builder.addProcessor(new AwsS3DiscoveryProcessor(env.reader));
+```