message: Added custom provider annotation details
diff: @@ -159,7 +159,12 @@ Check out the numbered markings - let's go through them one by one.
  the outcome of that. This example issues a `fetch` to the right service and
  issues a full refresh of its entity bucket based on that.
  5. The method translates the foreign data model to the native `Entity` form, as
  - expected by the catalog.
  + expected by the catalog. Make sure that in this method you include the
  + `backstage.io/managed-by-location` and `backstage.io/managed-by-origin-location`
  + annotations on your `Entity`. If these are not present they will not show up
  + in the Catalog and you will see warnings in your logs. The
  + [Well-known Annotations](./well-known-annotations.md#backstageiomanaged-by-location)
  + documentation has guidance on what values to use for these.
  6. Finally, we issue a "mutation" to the catalog. This persists the entities in
  our own bucket, along with an optional `locationKey` that's used for conflict
  checks. But this is a bigger topic - mutations warrant their own explanatory
  