update draft raspi notes

content/notes/raspberry-pi/index.md

@@ -41,6 +41,14 @@ $ nmcli device wifi list
 
 ### Moving to testing (from bookworm)
 
+Why would you want to do that in the first place? Well, most
+packages on debian _stable_ are quite old -- hence the name _stable_.
+
+If you need newer packages, you should consider moving to the _testing_
+branch. I moved my Raspberry Pi 4 to _testing_ because of the starship
+prompt that I use on my computers -- it needed a newer version of the
+`rustc` package.
+
 First of all, upgrade to the latest packages.
 
 ~~~console