Document changes and release 5.12.2pureos3~amber1 of linux-librem5

Signed-off-by: Martin Kepplinger <martin.kepplinger@puri.sm>
2 jobs for release5122_3_amber in 81 minutes and 1 second (queued for 25 minutes and 46 seconds)
Status Job ID Name Coverage
  Build
passed #352692
librem5
build:aarch64

00:57:57

passed #352693
librem5:arm64
build:deb

01:10:04