Update 'doc/release-process.md'

doc/release-process.md

@@ -124,3 +124,9 @@ Install deps on Linux:
 Use `./util/build-mac.sh` to compile on Apple/Mac systems, use `./util/build-win.sh` to build on Windows and `./util/build-arm.sh` to build on ARMv8 systems.
 
 Use `./util/build-debian-package.sh aarch64` to build a Debian package for aarch64 .
+
+## Optional things
+
+### Updating RandomX
+
+If you need to update the source code of our in tree copy of RandomX, see issue https://git.hush.is/hush/hush3/issues/337#issuecomment-5114 for details. Currently we use RandomX v1.2.1 from the official repo at https://github.com/tevador/RandomX/releases/tag/v1.2.1