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CONTRIBUTING.md

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+# Contributing
+
+We – [Delta10 B.V.](https://www.delta10.nl/) and the maintainers of this project – know we can only build together with you. Thus we appreciate your input, enjoy feedback and welcome improvements to this project and are very open to collaboration.
+
+By contributing to this project, you accept and agree the the terms and conditions as specified in the [Contributor Licence Agreement](CLA.md).
+
+## Problems, suggestions and questions in Issues
+
+You don't need to change any of our code or documentation to be a contributor. Please help development by reporting problems, suggesting changes and asking questions. To do this, you can [create a GitLab Issue](https://docs.gitlab.com/ee/user/project/issues/index.html#issues) for this project in the [issues section](https://gitlab.com/delta10/project-template/issues).
+
+## Documentation and code in Merge Requests
+
+If you want to add to the documentation or code of one of our projects you should push a branch and make a Merge Request. If you never used GitLab, get up to speed by reading about the [GitLab Flow](https://about.gitlab.com/2014/09/29/gitlab-flow/).
+
+### 1. Make your changes
+
+This project uses the **OneFlow branching model** and workflow. When you've forked this repository, please make sure to create a feature branch following the OneFlow model. Read this [short blogpost](http://endoflineblog.com/oneflow-a-git-branching-model-and-workflow) when you're not yet familiar with OneFlow.
+
+Add your changes in commits [with a message that explains them](https://robots.thoughtbot.com/5-useful-tips-for-a-better-commit-message). Document choices or decisions you make in the commit message, this will enable everyone to be informed of your choices in the future.
+
+If you are adding code, make sure you've added and updated the relevant documentation and tests before you submit your Merge Request. Make sure to write tests that show the behaviour of the newly added or changed code.
+
+### 2. Merge Request
+
+When submitting the Merge Request, please accompany it with a description of the problem you are trying to address and the issue numbers that this Merge Request fixes/addresses.
+
+### 3. Improve
+
+All contributions have to be reviewed by someone.
+
+It could be that your contribution can be merged immediately by a maintainer. However, usually, a new Merge Request needs some improvements before it can be merged. Other contributors (or our automatic testing system) might have feedback. If this is the case the reviewing maintainer will help you improve your documentation and code.
+
+If your documentation and code have passed human review and have passed the automated tests, it is merged.
+
+### 4. Celebrate
+
+Your ideas, documentation and code have become an integral part of this project.
+
+---
+
+For more information on how to use and contribute to this project, please read the [`README`](README.md).