I can not find anything specifically but I would suspect that you will have to do an incremental since you had to going up to 7.
I believe that this would be the upgrade path:
5.2.5 > 7.0.11 > 7.13.x > 8.0.2 (You might be able to skip 7.13.x)
Here's the upgrade documentation:
You should also check the supported platforms and ensure that you are good to go there: https://confluence.atlassian.com/adminjiraserver/supported-platforms-938846830.html?_ga=2.122344075.1417763911.1554129722-1785046573.1549295491
You can also submit a support ticket to confirm your upgrade path. https://support.atlassian.com/contact/
I'd be more careful with this. I agree with all with @Brant Schroeder , but I could go in this upgrade path (from my experience - my most interesting upgrade was from 3.x to 6.14).
current -> 6.0 -> 6.4 -> 7.0 -> 7.1 -> 7.13 -> 8.1
I know it's a lot of steps, but it's way how I should do it.
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