message: Clarify type generics in docs
diff: @@ -136,14 +136,22 @@ import { isOpenSearchCompatible } from '@backstage/plugin-search-backend-module-
  import { Client as ElasticClient } from '@elastic/elasticsearch';
  import { Client as OpenSearchClient } from '@opensearch-project/opensearch';
  -const client = searchEngine.newClient(options => {
  - // In reality, you would only import / instantiate one of the following, but
  - // for illustrative purposes, here are both:
  +// Return an Elasticsearch client
  +const esClient = searchEngine.newClient<ElasticClient>(options => {
  + if (!isOpenSearchCompatible(options)) {
  + return new ElasticClient(options);
  + }
  +
  + throw new Error('Incompatible options');
  +});
  +
  +// Return an OpenSearch client
  +const osClient = searchEngine.newClient<OpenSearchClient>(options => {
  if (isOpenSearchCompatible(options)) {
  return new OpenSearchClient(options);
  - } else {
  - return new ElasticClient(options);
  }
  +
  + throw new Error('Incompatible options');
  });
  ```
  