documentation: Fix naming, trademarks and licenses

Rename "Actuation Service demo" to "Safety Island Actuation Demo",
shortened to "Actuation Demo" appart from the headers and the first use
in the overview page. Keep the "Actuation Service" naming to refer to
the software running on the Safety Island.

Add missing trademarks.

Add missing license header.

Issue-Id: SCM-5892
Signed-off-by: Ambroise Vincent <ambroise.vincent@arm.com>
Change-Id: I53a6473424b7c34525d602fa54a472e436ea9146