Add changelog entry.

debian/changelog

@@ -3,7 +3,10 @@ livecd-rootfs (2.892) UNRELEASED; urgency=medium
   [ Gauthier Jolly ]
   * ubuntu-cpc: fix images for hardware devices
 
- -- Łukasz 'sil2100' Zemczak <lukasz.zemczak@ubuntu.com>  Mon, 26 Jun 2023 16:48:19 +0200
+  [ Heinrich Schuchardt ]
+  * RISC-V: use GRUB on Unmatched board. Simplify the code.
+
+ -- Łukasz 'sil2100' Zemczak <lukasz.zemczak@ubuntu.com>  Wed, 28 Jun 2023 10:42:31 +0200
 
 livecd-rootfs (2.891) mantic; urgency=medium