Replace md file with badge linking to documentation site. Fixes jaraco/skeleton#47.

Author: jaraco

README.rst

@@ -16,3 +16,6 @@
 
 .. .. image:: https://readthedocs.org/projects/skeleton/badge/?version=latest
 ..    :target: https://skeleton.readthedocs.io/en/latest/?badge=latest
+
+.. image:: https://img.shields.io/badge/skeleton-2021-informational
+   :target: https://blog.jaraco.com/skeleton