add docs badge

README.org

@@ -2,11 +2,7 @@
 [[https://github.com/AdrienWehrle/earthspy/actions][file:https://github.com/AdrienWehrle/earthspy/workflows/CI/badge.svg]]
 [[https://github.com/AdrienWehrle/earthspy/actions/workflows/codeql.yml][https://github.com/AdrienWehrle/earthspy/actions/workflows/codeql.yml/badge.svg]]
 
-#+begin_html
-<a href="https:/readthedocs.org/projects/earthspy/badge/?version=latest">
-<img src="https:/readthedocs.org/projects/earthspy/badge/?version=latest" />
-</a>
-#+end_html
+#+macro: travis [[https://travis-ci.org/kaushalmodi/ox-hugo][https://travis-ci.org/kaushalmodi/ox-hugo.svg?branch=master]]
 
 [[https://pre-commit.com/][https://img.shields.io/badge/pre--commit-enabled-brightgreen?logo=pre-commit.svg]]
 [[https://codecov.io/gh/AdrienWehrle/earthspy][https://codecov.io/gh/AdrienWehrle/earthspy/branch/main/graph/badge.svg]]