AutoML in User Guide: remove experimental note

Description

AutoML is not considered experimental so let's remove the last bullet (shown below) in the following section: http://docs.h2o.ai/h2o/latest-stable/h2o-docs/automl.html#additional-information

```
AutoML is currently in experimental mode (“V99” in the REST API). This means that, although unlikely, the API (REST, R, Python or otherwise) may be subject to breaking changes.
```

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Assignee

hannah.tillman

Fix versions

Reporter

Lauren DiPerna

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