website: fixed broken links, typos, formatting

Change-Id: Iddbf3333e96a85b6701f92b613fb6b2a369751d3
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5-website/+/31115
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Maintainer: Jason Lowe-Power <power.jg@gmail.com>
Tested-by: Jason Lowe-Power <power.jg@gmail.com>
5 files changed