Investigate how to build other REST API generated docs

As well as the Liberty API/SPI docs that we've discussed previously (and mentioned in the autogen epic), there are some OpenAPI REST API docs in the KC that Alasdair has previously said do need to come over the OL docs. These are API docs generated by OpenAPI for APIs that are provided to use with Liberty (Batch REST APIs, and JMX REST Connector REST APIs) (so, to be clear, this has nothing to do with the OL support for MicroProfile OpenAPI etc).

Alasdair's comment when we first audited the KC, was that we need to start by finding out how the KC is currently building these docs. Then, talk to Michal about how we get these docs built into the OL docs, and will probably need an issue creating then like we have for the API/SPI docs. That issue should probably be added to the autogen epic and prioritised with Alasdair against the other issues listed there.

Start by reviewing the OpenAPI REST API documentation in the linked KC page and the autogen epic (#2615) to determine how the Batch REST APIs and JMX REST Connector REST APIs are currently built. Discuss the findings with Michal and Alasdair; done means documenting the build approach and creating a prioritized follow-up issue for integrating these docs into the Open Liberty docs.