Fixing SSH key generation problem

Fixing SSH key generation problem

I installed Ubuntu 22.04 and RSA protocol for ssh key pair was not working and was constantly getting permission denined key pair mismatch issues.
After following openstac documentation (https://docs.openstack.org/contributors/common/setup-gerrit.html) I was quickly able to fix SSH key setup issue.
Open Stack recommended to use ed25519 keys protocol as it works well in all operating system.
Following that recommendation and personally experience issues with RSA key generation I have updated the documentation to ed25519.

Bug-AGL: [SPEC-4470]
Signed-off-by: Vinod Ahuja <vahuja@unomaha.edu>
Change-Id: I6209337e0056821ec9a0f28ea9aabb9d0933c53e
Reviewed-on: https://gerrit.automotivelinux.org/gerrit/c/AGL/documentation/+/27932
Reviewed-by: Jan-Simon Moeller <jsmoeller@linuxfoundation.org>
Tested-by: Jan-Simon Moeller <jsmoeller@linuxfoundation.org>