Merge pull request #382 from pyOpenSci/doc/star-history

docs: add star-history to README

Author: willingc

README.md

@@ -180,3 +180,7 @@ Thanks goes to these wonderful people ([emoji key](https://allcontributors.org/d
 <!-- ALL-CONTRIBUTORS-LIST:END -->
 
 This project follows the [all-contributors](https://github.com/all-contributors/all-contributors) specification. Contributions of any kind welcome!
+
+## Star History
+
+[![Star History Chart](https://api.star-history.com/svg?repos=pyOpenSci/python-package-guide&type=Date)](https://star-history.com/#pyOpenSci/python-package-guide&Date)