doc: update badges

Author: xuyxu

README.rst

@@ -1,6 +1,6 @@
 .. image:: ./docs/_images/badge_small.png
 
-|github|_ |readthedocs|_ |codecov|_ |python|_ |pypi|_ |license|_
+|github|_ |readthedocs|_ |codecov|_ |python|_ |pypi|_ |license|_ |commit_count|_
 
 .. |github| image:: https://github.com/xuyxu/Ensemble-Pytorch/workflows/torchensemble-CI/badge.svg
 .. _github: https://github.com/xuyxu/Ensemble-Pytorch/actions
@@ -20,6 +20,9 @@
 .. |license| image:: https://img.shields.io/github/license/xuyxu/Ensemble-Pytorch
 .. _license: https://github.com/xuyxu/Ensemble-Pytorch/blob/master/LICENSE
 
+.. |commit_count| image:: https://img.shields.io/github/commits-since/xuyxu/Ensemble-PyTorch/latest
+.. _commit_count: https://github.com/xuyxu/Ensemble-Pytorch
+
 Ensemble PyTorch
 ================