Merge pull request #249 from pybamm-team/docs_badge

Update docs badge in readme to develop

README.md

@@ -4,7 +4,7 @@
 <div align="center">
 
 [![liionpack](https://github.com/pybamm-team/liionpack/actions/workflows/test_on_push.yml/badge.svg)](https://github.com/pybamm-team/liionpack/actions/workflows/test_on_push.yml)
-[![Documentation Status](https://readthedocs.org/projects/liionpack/badge/?version=main)](https://liionpack.readthedocs.io/en/main/?badge=main)
+[![Documentation Status](https://readthedocs.org/projects/liionpack/badge/?version=develop)](https://liionpack.readthedocs.io/en/develop/?badge=develop)
 [![codecov](https://codecov.io/gh/pybamm-team/liionpack/branch/main/graph/badge.svg)](https://codecov.io/gh/pybamm-team/liionpack)
 [![Open In Colab](https://colab.research.google.com/assets/colab-badge.svg)](https://colab.research.google.com/github/pybamm-team/liionpack/blob/main/)
 [![DOI](https://joss.theoj.org/papers/10.21105/joss.04051/status.svg)](https://doi.org/10.21105/joss.04051)