doc: don't treat Sphinx build warnings as errors.

Author: dbrnz

.readthedocs.yml

@@ -15,4 +15,4 @@ build:
   commands:
     - pip install uv
     - uv sync --dev
-    - uv run python -m sphinx docs $READTHEDOCS_OUTPUT/html -b html -W
+    - uv run python -m sphinx docs $READTHEDOCS_OUTPUT/html -b html