Add CONTRIBUTIONS and rename LICENSE to markdown

CONTRIBUTIONS.md

+# Contributions
+
+## If you are interested in contributing, here are some ground rules:
+* Talk to us before doing the work -- we love contributions, but we might already be working on the same thing, or we might have different opinions on how it should be implemented.
+
+## All contributions are subject to the [Unity Contribution Agreement(UCA)](https://unity3d.com/legal/licenses/Unity_Contribution_Agreement)
+By making a pull request, you are confirming agreement to the terms and conditions of the UCA, including that your Contributions are your original creation and that you have complete right and authority to make your Contributions.
+
+## Once you have a change ready following these ground rules. Simply make a pull request in Github

CONTRIBUTIONS.md.meta

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