message: adding circle ci badge
diff: <img src="docs/source/bark_logo.png" alt="BArk" />
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  +[![CircleCI](https://circleci.com/gh/bark-simulator/bark.svg?style=svg)](https://circleci.com/gh/bark-simulator/bark)
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  # BArk - a tool for **B**ehavior benchm**Ark**ing
  BArk provides a semantic simulation tool/framework for autonomous agents with a special focus on autonomous driving.
  