docs/system/arm/fby35: document execute-in-place property

Reviewed-by: Cédric Le Goater <clg@redhat.com>
Signed-off-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
Message-id: 20241206192254.3889131-3-pierrick.bouvier@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

docs/system/arm/fby35.rst

@@ -45,3 +45,8 @@ process starts.
     $ screen /dev/tty0 # In a separate TMUX pane, terminal window, etc.
     $ screen /dev/tty1
     $ (qemu) c		   # Start the boot process once screen is setup.
+
+This machine model supports emulation of the boot from the CE0 flash device by
+setting option ``execute-in-place``. When using this option, the CPU fetches
+instructions to execute by reading CE0 and not from a preloaded ROM
+initialized at machine init time. As a result, execution will be slower.