update RTD config

Author: oraNod

.readthedocs.yaml

@@ -14,5 +14,4 @@ build:
     - python -m pip install --upgrade -r ./requirements.in -c ./requirements.txt
     - nikola build
     - mkdir -p _readthedocs/html/
-    - cp -r output/* _readthedocs/html/
-    - rm _readthedocs/html/robots.txt
+    - cp -r output/* sitemap.xml _readthedocs/html/