Index download speed while replicating is fixed at 5.1 in replication.html

[Florin Babes]

Hello,
While checking ways to optimize the speed of replication I've noticed that
the index download speed is fixed at 5.1 in replication.html. There is a
reason for that? If not, I would like to submit a patch with the fix.
We are using solr 8.3.1.
Thanks,
Florin Babes