Add missing default ML query descriptions (#2917)

Author: lcawl

output/openapi/elasticsearch-openapi.json

@@ -100,6 +100,7 @@ import { TextExpansionQuery } from './TextExpansionQuery'
 import { WeightedTokensQuery } from './WeightedTokensQuery'
 
 /**
+ * An Elasticsearch Query DSL (Domain Specific Language) object that defines a query.
  * @variants container
  * @non_exhaustive
  * @ext_doc_id query-dsl

output/openapi/elasticsearch-serverless-openapi.json

@@ -31,6 +31,11 @@ import { integer } from '@_types/Numeric'
  * Create a data frame analytics job.
  * This API creates a data frame analytics job that performs an analysis on the
  * source indices and stores the outcome in a destination index.
+ * By default, the query used in the source configuration is `{"match_all": {}}`.
+ *
+ * If the destination index does not exist, it is created automatically when you start the job.
+ *
+ * If you supply only a subset of the regression or classification parameters, hyperparameter optimization occurs. It determines a value for each of the undefined parameters.
  * @rest_spec_name ml.put_data_frame_analytics
  * @availability stack since=7.3.0 stability=stable
  * @availability serverless stability=stable visibility=public

output/schema/schema.json

@@ -39,7 +39,9 @@ import { Duration } from '@_types/Time'
  * Datafeeds retrieve data from Elasticsearch for analysis by an anomaly detection job.
  * You can associate only one datafeed with each anomaly detection job.
  * The datafeed contains a query that runs at a defined interval (`frequency`).
- * If you are concerned about delayed data, you can add a delay (`query_delay`) at each interval.
+ * If you are concerned about delayed data, you can add a delay (`query_delay') at each interval.
+ * By default, the datafeed uses the following query: `{"match_all": {"boost": 1}}`.
+ *
  * When Elasticsearch security features are enabled, your datafeed remembers which roles the user who created it had
  * at the time of creation and runs the query using those same roles. If you provide secondary authorization headers,
  * those credentials are used instead.

specification/_types/query_dsl/abstractions.ts

@@ -30,6 +30,7 @@ import { Duration } from '@_types/Time'
 /**
  * Create an anomaly detection job.
  * If you include a `datafeed_config`, you must have read index privileges on the source index.
+ * If you include a `datafeed_config` but do not provide a query, the datafeed uses `{"match_all": {"boost": 1}}`.
  * @rest_spec_name ml.put_job
  * @availability stack since=5.4.0 stability=stable
  * @availability serverless stability=stable visibility=public