ci(docs): set CNAME to Fortran-lang

Author: gnikit

.github/workflows/docs.yml

@@ -10,6 +10,10 @@ jobs:
         with:
           pre-build-command: "pip install .[docs]"
           docs-folder: "docs/"
+      - name: Set fortran-lang domain
+        if: github.ref == 'refs/heads/master'
+        run: |
+          echo fortls.fortran-lang.org > CNAME
       - name: Deploy
         uses: peaceiris/actions-gh-pages@v3
         if: github.ref == 'refs/heads/master'