add explanation for commented out code

Author: lawndoc

src/Dockerfile

@@ -13,7 +13,7 @@ COPY --from=ghcr.io/astral-sh/uv:latest /uv /uvx /bin/
 ADD . /restic-compose-backup
 WORKDIR /restic-compose-backup
 
-# RUN uv python install $(cat .python-version)
+# RUN uv python install $(cat .python-version)  # does not build for aarch64 -- see https://github.com/astral-sh/uv/issues/6890
 RUN uv sync --locked
 ENV PATH="/restic-compose-backup/.venv/bin:${PATH}"