Merge pull request #64 from unity/update-readme

Add clarification on contributions policy

README.md

 ## Interaction
 
 This sample scene demonstrates the functionality of the `XR Interaction Toolkit` package. In the scene, you are able to place a cube on a plane which you can translate, rotate and scale with gestures. See the [`XR Interaction Toolkit Documentation`](https://docs.unity3d.com/Packages/com.unity.xr.interaction.toolkit@0.9/manual/index.html) for more details.
+
+# Community and Feedback
+
+The intention of this reposititory is to provide a means for getting started with the features in ARFoundation. The samples are intentionally simplistic with a focus on teaching basic scene setup and APIs. If you you have a question, find a bug, or would like to request a new feature concerning any of the ARFoundation packages or these samples please [submit a GitHub issue](https://github.com/Unity-Technologies/arfoundation-samples/issues). New issues are reviewed regularly.
+
+## Contributions and Pull Requests
+
+We are not accepting pull requests at this time. If you find an issue with the samples, our would like to request a new sample, please [submit a GitHub issue](https://github.com/Unity-Technologies/arfoundation-samples/issues).

CONTRIBUTING.md

+# Contributing
+
+At this time, the repo is not accepting external contributions in the form of PRs. 
+
+We encourage you to submit bugs, suggestions, and feedback as [GitHub issues](https://github.com/Unity-Technologies/arfoundation-samples/issues).