Better formatting for "optional"

Co-authored-by: Emma Indal <emma.indahl@gmail.com>
Signed-off-by: Eric Peterson <ericpeterson@spotify.com>

plugins/search-indexer-backend/src/types.ts

@@ -90,7 +90,7 @@ export interface RegisterDecoratorParameters {
   decorator: IndexableDocumentDecorator;
 
   /**
-   * An optional array of document types that the given decorator should apply to. If none are provided,
+   * (Optional) An array of document types that the given decorator should apply to. If none are provided,
    * the decorator will be applied to all types.
    */
   types?: string[];