Document changes and release 5.11.11pureos1 of linux-librem5

Signed-off-by: Martin Kepplinger <martin.kepplinger@puri.sm>
2 jobs for pureos/byzantium in 64 minutes and 59 seconds (queued for 1 second)
Status Job ID Name Coverage
  Build
passed #339526
librem5
build:aarch64

00:18:28

passed #339527
librem5:arm64
build:deb

01:04:59