Add rerank task type specification

Author: timgrein

output/schema/schema.json

@@ -700,13 +700,26 @@ export class EisServiceSettings {
 }
 
 export enum EisTaskType {
-  chat_completion
+  chat_completion,
+  rerank
 }
 
 export enum EisServiceType {
   elastic
 }
 
+export class EisTaskSettings {
+  /**
+   * For a `rerank` task, return doc text within the results.
+   */
+  return_documents?: boolean
+
+  /**
+   * For a `rerank` task, the number of the top N documents that should be returned.
+   */
+  top_n?: integer
+}
+
 export class ElasticsearchServiceSettings {
   /**
    * Adaptive allocations configuration details.