fix zip structure?

.github/workflows/release.yml

@@ -45,7 +45,7 @@ jobs:
 
           OUT_BASE="${RUNNER_TEMP}/mkdocs_out"
           SITE="${OUT_BASE}/site"
-          SITE_OFFLINE="${OUT_BASE}/site_offline"
+          SITE_OFFLINE="${OUT_BASE}/site_offline/${GITHUB_REF_NAME}"
 
           rm -rf "${OUT_BASE}"
           mkdir -p "${SITE}" "${SITE_OFFLINE}"
@@ -56,8 +56,8 @@ jobs:
       - name: Zip offline site
         run: |
           set -euo pipefail
-          cd "${RUNNER_TEMP}/mkdocs_out"
-          zip -r "${GITHUB_REF_NAME}.zip" site_offline
+          cd "${RUNNER_TEMP}/mkdocs_out/site_offline/"
+          zip -r "${GITHUB_REF_NAME}.zip" ./${GITHUB_REF_NAME}
 
       - name: Publish prerelease
         if: startsWith(github.ref_name, 'rc')