The step between H.08 and H.10 sofware branches regards specifically latest H.08.109 and first H.10.20 released many years ago (see, as example, H.10.74 Release Notes)...but the H.08.98 software version (the one your Switch is currently running on) is, in effect, the intermediate step software version required for Switches running on older H.07 software branch to be upgraded to latest H.08.1xx software releases (and, as extension, I think to any H.10.xxx software release that has been released after H.08)...that's to say that available Release Notes documents don't report any other particular intermediate step if you start already from H.08.98.
To be conservative I will eventually jump to H.08.109 and then H.10.20 but, given that those software releases are unobtanium now (at least taking this page as reference), if I were you I will take the risk to jump directly to latest H.10.119 released during 2016.
Do backup of your current startup configuration (if aligned with your current running configuration) in any case.
