This commit adds documentation for the DLS/FLS restriction for RCS 2.0 API keys
where both access and replication are defined and access has DSL/FLS.
This commit also fixes a few misleading variable names.
related: #108600
**Problem:**
For historical reasons, source files for the Elasticsearch Guide's security, watcher, and Logstash API docs are housed in the `x-pack/docs` directory. This can confuse new contributors who expect Elasticsearch Guide docs to be located in `docs/reference`.
**Solution:**
- Move the security, watcher, and Logstash API doc source files to the `docs/reference` directory
- Update doc snippet tests to use security
Rel: https://github.com/elastic/platform-docs-team/issues/208
Jake Landis
florent-leborgne
James Rodewig