CHANGELOG.md: Mention various ARM errata

Signed-off-by: George Dunlap <george.dunlap@citrix.com>
Acked-by: Julien Grall <jgrall@amazon.com>
---
v2:
 - Tweaked wording
CC: Ian Jackson <ian.jackson@citrix.com>
CC: Stefano Stabellini <sstabellini@kernel.org>
CC: Julien Grall <julien@xen.org>

CHANGELOG.md

@@ -24,6 +24,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
  - Added XEN_SCRIPT_DIR configuration option to specify location for Xen scripts, rather than hard-coding /etc/xen/scripts
  - xennet: Documented a way for the backend (or toolstack) to specify MTU to the frontend
  - Some additional affordances in various xl subcommands.
+ - Added workarounds for the following ARM errata: Cortex A53 #843419, Cortex A55 #1530923, Cortex A72 #853709, Cortex A73 #858921, Cortex A76 #1286807, Neoverse-N1 #1165522
 
 ### Removed / support downgraded