minor fix

Author: jzstark

.github/workflows/main.yml

@@ -29,7 +29,7 @@ jobs:
         run: | 
             opam exec -- dune build @doc 
             cat docs/mathjax.js docs/highlight.pack.js >> _build/default/_doc/_html/highlight.pack.js
-	          cp -r _build/default/_doc/_html/* docs
+            cp -r _build/default/_doc/_html/* docs
       
       - name: Deploy
         uses: peaceiris/actions-gh-pages@v3