Update the job-scheduler plugin documentation with the list of supported API's

[prudhvigodithi]

Is your feature request related to a problem?

The job-scheduler plugin has the following API's which are added as part of the extensions effort.

Related issues

opensearch-project/opensearch-sdk-java#274
opensearch-project/opensearch-sdk-java#370

Related PR's

#289
#312

Get Job Details :

curl -XPUT localhost:9200/_plugins/_job_scheduler/_get/_job_details --data '{"job_index":"<job_index_name>","job_type":"<job_type>","job_parameter_action":"<job_parameter_action_name>","job_runner_action":"<job_runner_action_name>","extension_unique_id":"<extension_unique_id>"}' -H "Content-Type:application/json"

Update Job Details :

curl -XPUT localhost:9200/_plugins/_job_scheduler/_get/_job_details/{<documentId>} --data '{"job_index":"<job_index_name>","job_type"<job_type>","job_parameter_action":"<job_parameter_action_name>","job_runner_action":"<job_runner_action_name>","extension_unique_id":"<extension_unique_id>"}' -H "Content-Type:application/json"

Get Lock :

curl -XGET localhost:9200/_plugins/_job_scheduler/_lock/ --data '{"job_id":"<job_id>","job_index_name":"<job_index_name>","lock_duration_seconds":"<lock_duration_seconds>"}' -H "Content-Type:application/json"

Release Lock :

curl -XPUT localhost:9200/_plugins/_job_scheduler/_release_lock/{<lock_id>}

What solution would you like?
The API's should be documented in https://opensearch.org/docs/latest/monitoring-your-cluster/job-scheduler/index/ and in https://opensearch-project.github.io/opensearch-api-specification/.

[prudhvigodithi]

[Triage]
Adding @joshpalis @saratvemulapalli @dbwiddis @kaituo @vibrantvarun @cwperks @dblock @getsaurabh02

[cwperks]

These endpoints only make sense in the context of extensions so I think any documentation of these APIs should exist with extensions developer documentation like DESIGN.md of the opensearch-sdk-java repo.

These endpoints replace existing transport actions for out-of-process extensions.