adds notice

Author: stockholmux

index.md

@@ -79,3 +79,8 @@ If you want to modify the Open Distro code and build from source, instructions a
 [Open Distro](https://opendistro.github.io/for-elasticsearch/) is supported by Amazon Web Services. All components are available under the [Apache License, Version 2.0](https://www.apache.org/licenses/LICENSE-2.0.html) on [GitHub](https://github.com/opendistro-for-elasticsearch/).
 
 The project welcomes GitHub issues, bug fixes, features, plugins, documentation---anything at all. To get involved, see [Contribute](https://opendistro.github.io/for-elasticsearch/contribute.html) on the Open Distro website.
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+<small>OpenSearch includes certain Apache-licensed Elasticsearch code from Elasticsearch B.V. and other source code. Elasticsearch B.V. is not the source of that other source code. ELASTICSEARCH is a registered trademark of Elasticsearch B.V.</small>