Update readme for v1.4 release

Update the release notes (readme.rst) for the ARM Trusted Firmware v1.4 release.

Also, reorder and fix some of the links following the conversion to
reStructured text format.

Change-Id: I8f5e8aa86cb891f61b6b62cf9fab0ad0f0ebb36b
Signed-off-by: Dan Handley <dan.handley@arm.com>
1 file changed