Tweak revision-codes Note

Fixes #4119

Author: lurch

documentation/asciidoc/computers/raspberry-pi/revision-codes.adoc

@@ -15,7 +15,7 @@ Revision    : a02082
 Serial      : 00000000765fc593
 ----
 
-NOTE: All Raspberry Pi computers report `BCM2835`, even those with BCM2836, BCM2837, BCM2711, and BCM2712 processors. You should not use this string to detect the processor. Decode the revision code using the information below, or `cat /sys/firmware/devicetree/base/model`.
+NOTE: All Raspberry Pi computers report `BCM2835`, even those with BCM2836, BCM2837, BCM2711, and BCM2712 processors. You should not use this string to detect the processor. Decode the revision code using the information below, or `cat /sys/firmware/devicetree/base/model`. Depending on which kernel you're running, your `cpuinfo` might also have a "Model" line, and might not have a "Hardware" line.
 
 === Old-style revision codes