BUG: fixed documentation badge

Readthedocs badge link changed, update it to point to the right place.

README.md

@@ -4,7 +4,7 @@
 </div>
 
 # pysatMadrigal
-[![Documentation Status](https://readthedocs.org/projects/pysatMadrigal/badge/?version=latest)](http://pysatMadrigal.readthedocs.io/en/latest/?badge=latest)
+[![Documentation Status](https://readthedocs.org/projects/pysatmadrigal/badge/?version=latest)](https://pysatmadrigal.readthedocs.io/en/latest/?badge=latest)
 [![Build Status](https://travis-ci.org/pysat/pysatMadrigal.svg?branch=main)](https://travis-ci.com/pysat/pysatMadrigal)
 [![Coverage Status](https://coveralls.io/repos/github/pysat/pysatMadrigal/badge.svg?branch=main)](https://coveralls.io/github/pysat/pysatMadrigal?branch=main)
 [![DOI](https://zenodo.org/badge/258384773.svg)](https://zenodo.org/badge/latestdoi/258384773)