[DOCS] Add overlays for ML examples

[lcawl]

Relates to #2482

This PR converts machine learning example files from JSON to YAML format (to be able to comment out unsupported fields).
It then updates the overlays to incorporate those examples in the OpenAPI output.

[github-actions]

Following you can find the validation results for the APIs you have changed.

API	Status	Request	Response
ml.clear_trained_model_deployment_cache	🟢	1/1	1/1
ml.close_job	🟢	64/64	63/63
ml.delete_calendar_event	🟢	4/4	4/4
ml.delete_calendar_job	🟢	3/3	3/3
ml.delete_calendar	🟢	5/5	5/5
ml.delete_data_frame_analytics	🟢	2/2	2/2
ml.delete_datafeed	🟢	3/3	3/3
ml.delete_expired_data	🟢	5/5	5/5
ml.delete_filter	🟢	27/27	27/27
ml.delete_forecast	🟢	3/3	3/3
ml.delete_job	🟢	47/47	47/47
ml.delete_model_snapshot	🟢	2/2	2/2
ml.delete_trained_model_alias	🟢	3/3	3/3
ml.delete_trained_model	🟢	5/5	5/5
ml.open_job	🟢	83/83	83/83
ml.put_job	🟢	227/227	225/225
nodes.info	🔴	114/114	1/114

You can validate these APIs yourself by using the make validate target.

[github-actions]

Following you can find the validation results for the APIs you have changed.

API	Status	Request	Response
ml.clear_trained_model_deployment_cache	🟢	1/1	1/1
ml.close_job	🟢	64/64	63/63
ml.delete_calendar_event	🟢	4/4	4/4
ml.delete_calendar_job	🟢	3/3	3/3
ml.delete_calendar	🟢	5/5	5/5
ml.delete_data_frame_analytics	🟢	2/2	2/2
ml.delete_datafeed	🟢	3/3	3/3
ml.delete_expired_data	🟢	5/5	5/5
ml.delete_filter	🟢	27/27	27/27
ml.delete_forecast	🟢	3/3	3/3
ml.delete_job	🟢	47/47	47/47
ml.delete_model_snapshot	🟢	2/2	2/2
ml.delete_trained_model_alias	🟢	3/3	3/3
ml.delete_trained_model	🟢	5/5	5/5
ml.estimate_model_memory	🟢	16/16	16/16
ml.evaluate_data_frame	🟢	15/15	15/15
ml.explain_data_frame_analytics	🟢	7/7	7/7
ml.open_job	🟢	83/83	83/83
ml.put_job	🟢	227/227	225/225
nodes.info	🔴	114/114	1/114

You can validate these APIs yourself by using the make validate target.

[kilfoyle]

LGTM! 🐭