Document changes and release 5.13.19pureos3~amber1 of linux-librem5

Signed-off-by: Martin Kepplinger <martink@posteo.de>
2 jobs for release51319_3_amber in 87 minutes and 51 seconds (queued for 7 minutes and 38 seconds)
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Status Name Job ID Coverage
  Build
passed build:aarch64 #373686
librem5

00:16:14

passed build:deb #373687
librem5:arm64

01:11:37