GitLab

Since commit 3bff910d

 ("Introduce COT
build option"), it is now possible to select a different Chain of Trust
than the TBBR-Client one.

Make a few adjustments in the documentation to reflect that. Also make
some minor improvements (fixing typos, better formatting, ...)  along
the way.

Change-Id: I3bbadc441557e1e13311b6fd053fdab6b10b1ba2
Signed-off-by: Sandrine Bailleux <sandrine.bailleux@arm.com>