Updated the document for BL1 and BL2 boot flow to capture
below changes made in FCONF

1. Loading of fw_config and tb_fw_config images by BL1.
2. Population of fw_config and tb_fw_config by BL2.

Signed-off-by: Manish V Badarkhe <Manish.Badarkhe@arm.com>
Change-Id: Ifea5c61d520ff1de834c279ce1759b53448303ba

Update the plantuml diagrams to match the latest modification in fconf.

Signed-off-by: Louis Mayencourt <louis.mayencourt@arm.com>
Change-Id: I90f55bba0fd039a3f7e1bd39661cf849fccd64f5

Change-Id: I606f9491fb6deebc6845c5b9d7db88fc5c895bd9
Signed-off-by: Louis Mayencourt <louis.mayencourt@arm.com>