Document changes and release 5.9.16+librem5.1 of linux-librem5
Signed-off-by: Martin Kepplinger martin.kepplinger@puri.sm
Important note: With this stable update, 5.9 is EOL. Please run (and file bugs against) linux-image-5.11.0-1-librem5 which is tagged/released as "next" so that we can soon update to it.