I would expect that you could upgrade from 7.3.1 directly to 7.3.6. However, given the upgrade path that you linked and how simple it is I would first upgrade to 7.3.2 and then upgrade to 7.6.0.
Horizon 7 Upgrades
Just make sure that the versions of vCenter, ESXi, VMware Tools, UAG/Access Point, Horizon Client or zero/thin clients that you may be running are supported with Horizon 7.6.0. You will also want to check with any other VMware or third-party solutions that integrate with the environment.
