MAINTAINERS: add myself as a route for gitdm updates

Seeing as I'll get pegged by get_maintainers.pl anyway I might as well
make the support status of the data mining config official.
Signed-off-by: NAlex Bennée <alex.bennee@linaro.org>

MAINTAINERS

@@ -2494,6 +2494,12 @@ M: Daniel P. Berrange <berrange@redhat.com>
 S: Odd Fixes
 F: docs/devel/build-system.txt
 
+GIT Data Mining Config
+M: Alex Bennée <alex.bennee@linaro.org>
+S: Odd Fixes
+F: gitdm.config
+F: contrib/gitdm/*
+
 Incompatible changes
 R: libvir-list@redhat.com
 F: qemu-deprecated.texi