Document changes and release 5.12.0~rc6pureos1~amber1 of linux-next-librem5

Signed-off-by: Martin Kepplinger <martin.kepplinger@puri.sm>
2 jobs for next/amber-phone in 76 minutes and 26 seconds (queued for 13 minutes and 40 seconds)
Status Job ID Name Coverage
  Build
passed #339577
librem5
build:aarch64

00:47:02

passed #339578
librem5:arm64
build:deb

01:08:24