Document changes and release 5.11.11pureos1 of linux-librem5

Signed-off-by: Martin Kepplinger <martin.kepplinger@puri.sm>
2 jobs for release51111 in 62 minutes and 44 seconds
Status Job ID Name Coverage
  Build
passed #339522
librem5
build:aarch64

00:19:01

passed #339523
librem5:arm64
build:deb

01:02:43