Update codeowners for sphinx conf (#67548)
Summary:
Add a codeowner for the conf file to ensure allowlist modification is monitored.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/67548
Reviewed By: jbschlosser
Differential Revision: D32023929
Pulled By: albanD
fbshipit-source-id: 63f18cdd725cc60993a6c0a9e3529ed95845e0bb
