Add new release note files to Sphinx toctree for proper documentation rendering

Co-authored-by: leofang <5534781+leofang@users.noreply.github.com>

Author: Copilot

cuda_bindings/docs/source/release.rst

@@ -7,8 +7,10 @@ Release Notes
 .. toctree::
    :maxdepth: 3
 
+   13.X.Y <release/13.X.Y-notes.rst>
    13.0.1 <release/13.0.1-notes.rst>
    13.0.0 <release/13.0.0-notes.rst>
+   12.9.X <release/12.9.X-notes.rst>
    12.9.2 <release/12.9.2-notes.rst>
    12.9.1 <release/12.9.1-notes.rst>
    12.9.0 <release/12.9.0-notes.rst>