Apply suggestions from code review

Author: tkoyama010

README.md

@@ -1,5 +1,5 @@
 # <img src="https://www.pyopensci.org/images/logo.png" width=100 /> pyOpenSci scientific Python Packaging Guide
-[![All Contributors](https://img.shields.io/github/all-contributors/pyOpenSci/python-package-guide?color=ee8449)](#contributors)
+[![All Contributors](https://img.shields.io/github/all-contributors/pyOpenSci/python-package-guide?color=ee8449)](#contributors-)
 
 ![GitHub release (latest by date)](https://img.shields.io/github/v/release/pyopensci/python-package-guide?color=purple&display_name=tag&style=plastic)