Add base_url

Author: giswqs

.github/workflows/deploy.yml

@@ -44,6 +44,9 @@ jobs:
         run: npm install -g mystmd
 
       - name: Build HTML Assets
+        # Remove BASE_URL if using a custom domain (CNAME)
+        env:
+          BASE_URL: /${{ github.event.repository.name }}
         run: myst build --html
 
       - name: Generate RSS and Atom feeds