Update changelog markdown for 0.21.0

Author: mattstratton

CHANGELOG.md

@@ -1,5 +1,16 @@
 # Change Log
 
+## [0.21.0](https://github.com/devopsdays/devopsdays-cli/tree/0.21.0) (2017-10-20)
+[Full Changelog](https://github.com/devopsdays/devopsdays-cli/compare/0.20.1...0.21.0)
+
+**Implemented enhancements:**
+
+- Shorter name for the binary? [\#116](https://github.com/devopsdays/devopsdays-cli/issues/116)
+
+**Fixed bugs:**
+
+- Need to add abiilty to quit application at all prompts [\#119](https://github.com/devopsdays/devopsdays-cli/issues/119)
+
 ## [0.20.1](https://github.com/devopsdays/devopsdays-cli/tree/0.20.1) (2017-10-08)
 [Full Changelog](https://github.com/devopsdays/devopsdays-cli/compare/0.20.0...0.20.1)