fix sed usage

stupid BRE...

.github/workflows/pages.yml

@@ -35,7 +35,7 @@ jobs:
       - name: Generate Index
         shell: bash
         run: |
-          find . -name javadoc -type d -print | sed -i 's#^\./(.*)/javadoc$#\1#' > index.txt
+          find . -name javadoc -type d -print | sed 's#^\./\(.*\)/javadoc$#\1#' > index.txt
       - name: Upload artifact
         uses: actions/upload-pages-artifact@v1
         with: