add nss-mdns for local service discovery, #12730
doc: explain global.official

Fix documentation following an earlier patch
3b528230dfae4792e58ab2c1c7f0da8b80463c36, where "UNOFFICIAL" was
replaced with "customized" (sic),

Also, base.official was always global.official.
13.2.1: configs copied from 13.2.0
13.2.1: delete 13.2.0 configs
13.2.1: configs: change release and repositories

- increment the release, from 13.2.0 to 13.2.1,

- keep using the hardware independent 13.2.0 frozen repository,

- use a new 13.2.1 hardware specific frozen repository, which is a clone
  of the 13.2.0 with new kernel and firmware only,
v7.0.2 release