Fix deploy docs action to preserve files

.github/workflows/deploy-docs.yml

@@ -32,7 +32,13 @@ jobs:
 
       - name: Build Docs with sphinx-multiversion
         run: |
-          poetry run sphinx-multiversion docs docs/_build/html
+          if [ "${{ github.ref }}" == "refs/heads/main" ]; then
+            OUTDIR=docs/_build/html
+          else
+            BRANCH_NAME=$(echo ${{ github.ref }} | sed 's,refs/heads/,,; s,refs/tags/,,')
+            OUTDIR=docs/_build/html/${BRANCH_NAME}
+          fi
+          poetry run sphinx-multiversion docs $OUTDIR
 
       - name: Prepare Deployment
         run: |
@@ -45,3 +51,4 @@ jobs:
         with:
           github_token: ${{ secrets.GITHUB_TOKEN }}
           publish_dir: ./docs/_build/html
+          keep_files: true  # Keeps existing files at deployment location