Details:
1. Adds AN524 platform support files
2. Adds a new target platform to the build system: "AN524"
3. Updates the docs with details for AN524

Change-Id: I7c192e951253dfc72512d73ee5da3f94023a248f
Signed-off-by: Kevin Peng <kevin.peng@arm.com>

Jamie Fox authored Jun 05, 2019 and Tamas Ban committed Jun 19, 2019

Updates documents to consistently refer to Musca-A, rather than using a
mix of Musca-A and Musca-A1.

Change-Id: I6f7a9e6afe3475b4a88200f6e56bf4c5507850e4
Signed-off-by: Jamie Fox <jamie.fox@arm.com>

The official documentation format for TF-M is becoming Restructured
Text. This change converts the existing .md files to the new format.

Due to support for documentation of external code (/lib) md support is
kept.

Change-Id: I3c1aef5d22442e0c7c362a40a8d344a266dc0940
Signed-off-by: Gyorgy Szing <Gyorgy.Szing@arm.com>