OpenSearch/.github/PULL_REQUEST_TEMPLATE.md

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- Have you signed the [contributor license agreement](https://www.elastic.co/contributor-agreement)?
- Have you followed the [contributor guidelines](https://github.com/elastic/elasticsearch/blob/master/CONTRIBUTING.md)?
- If submitting code, have you built your formula locally prior to submission with `gradle check`?
- If submitting code, is your pull request against master? Unless there is a good reason otherwise, we prefer pull requests against master and will backport as needed.
- If submitting code, have you checked that your submission is for an [OS that we support](https://www.elastic.co/support/matrix#show_os)?
- If you are submitting this code for a class then read our [policy](https://github.com/elastic/elasticsearch/blob/master/CONTRIBUTING.md#contributing-as-part-of-a-class) for that.