docs: fix indentation of GITHUB_TOKEN env in the README's usage section

README.md

@@ -55,9 +55,9 @@ Available as github action. It can automatically generate a new image each day.
       dist/github-snake-dark.svg?palette=github-dark
       dist/ocean.gif?color_snake=orange&color_dots=#bfd6f6,#8dbdff,#64a1f4,#4b91f1,#3c7dd9
 
-    env:
-      # a github token is required to fetch the contribution calendar from github API
-      GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+  env:
+    # a github token is required to fetch the contribution calendar from github API
+    GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
 ```
 
 [example with cron job](https://github.com/Platane/Platane/blob/master/.github/workflows/main.yml#L25-L33)