added CII best practices badge status

README.md

@@ -1,4 +1,5 @@
 [![Build Status](https://travis-ci.org/sovereign/sovereign.svg?branch=master)](https://travis-ci.org/sovereign/sovereign)
+[![CII Best Practices](https://bestpractices.coreinfrastructure.org/projects/460/badge)](https://bestpractices.coreinfrastructure.org/projects/460)
 
 Introduction
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