Add summaries for machine learning APIs (#2453)

Author: lcawl

output/openapi/elasticsearch-openapi.json

@@ -22,7 +22,7 @@ import { Id } from '@_types/common'
 import { Duration } from '@_types/Time'
 
 /**
- * Close anomaly detection jobs
+ * Close anomaly detection jobs.
  * A job can be opened and closed multiple times throughout its lifecycle. A closed job cannot receive data or perform analysis operations, but you can still explore and navigate results.
  * When you close a job, it runs housekeeping tasks such as pruning the model history, flushing buffers, calculating final results and persisting the model snapshots. Depending upon the size of the job, it could take several minutes to close and the equivalent time to re-open. After it is closed, the job has a minimal overhead on the cluster except for maintaining its meta data. Therefore it is a best practice to close jobs that are no longer required to process data.
  * If you close an anomaly detection job whose datafeed is running, the request first tries to stop the datafeed. This behavior is equivalent to calling stop datafeed API with the same timeout and force parameters as the close job request.

output/openapi/elasticsearch-serverless-openapi.json

@@ -21,8 +21,7 @@ import { RequestBase } from '@_types/Base'
 import { Id } from '@_types/common'
 
 /**
- * Deletes an anomaly detection job.
- *
+ * Delete an anomaly detection job.
  * All job configuration, model state and results are deleted.
  * It is not currently possible to delete multiple jobs using wildcards or a
  * comma separated list. If you delete a job that has a datafeed, the request