In particular, 'system/service credentials' are now described as simply
'credentials'. The selling point of credentials is that they are transparently
propagated from the system to services, so distinguishing between system and
service credentials is not important.
The description of ordering against initrd-switch-root.target is completely
rewritten. The old description was confused.
I think the description of systemd-measure should be reworked to clearly
describe what new functionality is provided and what policy changes are
built on top. But I don't qrok the details, so I left this part unchanged.