website: Fix MAINTAINER links

The MAINTAINERS.md file has been replaced with the MAINTAINERS.yaml
file. This requires the website to be updated accordingly.

Change-Id: Id51eaec77a08fd0a38a15c3830a16b9f95187fd5
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5-website/+/55684
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Tested-by: Jason Lowe-Power <power.jg@gmail.com>
Maintainer: Bobby Bruce <bbruce@ucdavis.edu>
2 files changed