doc: Update page content after re-arrangement

This patch modifies the content of existing documents now that
it has been moved around. Some of the content requires updating
to make sense in its new location, for example. Other content may
simply be out of date.

Change-Id: I8dfa527e1d1f1520cefd21066802451352b573d2
Signed-off-by: Paul Beesley <paul.beesley@arm.com>
Signed-off-by: Jimmy Brisson <jimmy.brisson@arm.com>
11 files changed