docs: name both Linux architectures in the release notes

The artifact list said Linux x64 AppImage, but the release carries an
x86_64 and an aarch64 image.

Author: tyza66

packaging/release-notes.md

@@ -5,7 +5,7 @@ memory defaults, QEMU and ARM firmware. Select a compatible bootable guest disk
 on first Start; the disk selection is saved for subsequent launches.
 
 Artifacts: Windows x64 NSIS installer, macOS Apple Silicon and Intel DMGs,
-Linux x64 AppImage, and SHA256SUMS.
+Linux x64 and ARM64 AppImages, and SHA256SUMS.
 
 The installers bundle the QEMU compatibility layer and Android Platform Tools.
 A prepared bootable Linux/Android guest disk is still a separate prerequisite.