Added Python ML examples to the API docs

[iuliaferoli]

New batch of examples, as per https://github.com/elastic/elasticsearch-py/issues/2429

❌ Found an issue with function update-trained-model-deployment not appearing in the spec / not running - waiting for feedback on this before going ahead with the example.

✅ The rest of the examples run as expected.

❌ Docs issue: This page for Create trained model definition part API isn't shown on the list of ML APIs here