Did a few things:
* Rewrite Kibana docs asciidoc links to be MD links
* Make kibana docs links absolute to planned publication path
* Clarify which operators are generated and which are static
* Removed the trailing .md from kibana docs links
Building on the work started in https://github.com/elastic/elasticsearch/pull/123904, we now want to auto-generate most of the small subfiles from the ES|QL functions unit tests.
This work also investigates any remaining discrepancies between the original asciidoc version and the new markdown, and tries to minimize differences so the docs do not look too different.
The kibana json and markdown files are moved to a new location, and the operator docs are a little more generated than before (although still largely manual).
Craig Taverner