MAINTAINERS: Add docs/requirements.txt

Add docs/requirements.txt to
"Sphinx documentation configuration and build machinery".

Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Signed-off-by: John Snow <jsnow@redhat.com>
Message-ID: <20250715212848.171879-3-jsnow@redhat.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>

MAINTAINERS

@@ -4428,6 +4428,7 @@ M: Peter Maydell <peter.maydell@linaro.org>
 S: Maintained
 F: docs/conf.py
 F: docs/*/conf.py
+F: docs/requirements.txt
 F: docs/sphinx/
 F: docs/_templates/
 F: docs/devel/docs.rst