* [DOCS] Adds regression analytics resources and examples to the data frame analytics APIs.
Co-Authored-By: Benjamin Trent <ben.w.trent@gmail.com>
Co-Authored-By: Tom Veasey <tveasey@users.noreply.github.com>
This PR addresses the feedback in https://github.com/elastic/ml-team/issues/175#issuecomment-512215731.
* Adds an example to `analyzed_fields`
* Includes `source` and `dest` objects inline in the resource page
* Lists `model_memory_limit` in the PUT API page
* Amends the `analysis` section in the resource page
* Removes Properties headings in subsections
