Document changes and release 5.12.2pureos4~amber1 of linux-librem5

Signed-off-by: Martin Kepplinger <martin.kepplinger@puri.sm>
2 jobs for release5122_4_amber in 79 minutes and 31 seconds (queued for 52 minutes and 43 seconds)
Status Job ID Name Coverage
  Build
passed #353733
librem5
build:aarch64

00:40:38

passed #353734
librem5:arm64
build:deb

01:09:03