The rebalance op links to the multi-hdd page, but the multi-hdd page
does not refer to the rebalance op description and only states that an
operator can launch a repair procedure without stating which procedure.
Add a link to the rebalance repair procedure in the multi-hdd page to
make it easier to find what procedure to run for rebalance.
Reviewed-on: https://git.deuxfleurs.fr/Deuxfleurs/garage/pulls/1491
Agathe Porte