minor: Update documentation badge

README.md

@@ -3,7 +3,7 @@
 <img src="https://user-images.githubusercontent.com/1189580/169594012-2d685579-2b66-4470-9def-57bd0656b420.png" align="right" width="300">
 
 [![Packaging](https://img.shields.io/github/actions/workflow/status/upkie/upkie_description/packaging.yml?branch=main)](https://github.com/upkie/upkie_description/actions)
-[![Documentation](https://img.shields.io/badge/docs-read-brightgreen?logo=read-the-docs&style=flat)](https://github.com/upkie/upkie_description/wiki)
+[![Documentation](https://img.shields.io/badge/docs-wiki-brightgreen?style=flat)](https://github.com/upkie/upkie_description/wiki)
 [![Conda version](https://img.shields.io/conda/vn/conda-forge/upkie_description.svg)](https://anaconda.org/conda-forge/upkie_description)
 [![PyPI version](https://img.shields.io/pypi/v/upkie_description)](https://pypi.org/project/upkie_description/)