Add MIT license badge

README.md

@@ -7,6 +7,7 @@
 [![Maintainability Rating](https://sonarcloud.io/api/project_badges/measure?project=TylerHendrickson_mydyndns&metric=sqale_rating)](https://sonarcloud.io/summary/new_code?id=TylerHendrickson_mydyndns)
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+[![GitHub license](https://img.shields.io/github/license/TylerHendrickson/mydyndns.svg)](https://github.com/TylerHendrickson/mydyndns/blob/master/LICENSE)
 
 A client for the mydyndns dynamic DNS service, providing an application library, CLI tools,
 and agent process for keeping DNS entries up-to-date.