Upgrading a 3.52 SRS HA pair to Secure Connect Gateway

Are there any documents that outline how to upgrade a 3.52 SRS HA Pair to Secure Connect Gateway?

I have searched the available documentation and can't find anything on this subject

Question from my customer

with a 2 node cluster gateway pair and Policy Manager 7.0, how should I go about upgrading the same gateways from 3.52.20.08 to SCG 5.00?