motd: update to show Amazon Linux 2023

Author: maherthomsi

motd

@@ -3,8 +3,8 @@
    ╱┄┄╲   This container provides access to the Bottlerocket host
    │▗▖│   filesystems (see /.bottlerocket/rootfs) and contains common
   ╱│  │╲  tools for inspection and troubleshooting.  It is based on
-  │╰╮╭╯│  Amazon Linux 2, and most things are in the same places you
-    ╹╹    would find them on an AL2 host.
+  │╰╮╭╯│  Amazon Linux 2023, and most things are in the same places you
+    ╹╹    would find them on an AL20203 host.
 
 To permit more intrusive troubleshooting, including actions that mutate the
 running state of the Bottlerocket host, we provide a tool called "sheltie"