Documentation: update tested platforms

Update both the readme and user guide on their shared "platform"
section.

Change-Id: Ia1f30acda45ac8facdcb7d540800191cdf6cdacf
Signed-off-by: Ambroise Vincent <ambroise.vincent@arm.com>
diff --git a/docs/user-guide.rst b/docs/user-guide.rst
index 33d7621..1e06580 100644
--- a/docs/user-guide.rst
+++ b/docs/user-guide.rst
@@ -1658,6 +1658,8 @@
 -  ``FVP_Base_Cortex-A53x4``
 -  ``FVP_Base_Cortex-A55x4+Cortex-A75x4``
 -  ``FVP_Base_Cortex-A55x4``
+-  ``FVP_Base_Cortex-A57x1-A53x1``
+-  ``FVP_Base_Cortex-A57x2-A53x4``
 -  ``FVP_Base_Cortex-A57x4-A53x4``
 -  ``FVP_Base_Cortex-A57x4``
 -  ``FVP_Base_Cortex-A72x4-A53x4``
@@ -1667,7 +1669,11 @@
 -  ``FVP_Base_Cortex-A75x4``
 -  ``FVP_Base_Cortex-A76x4``
 -  ``FVP_Base_Neoverse-N1x4`` (Tested with internal model)
+-  ``FVP_Base_Deimos``
 -  ``FVP_CSS_SGI-575`` (Version 11.3 build 42)
+-  ``FVP_CSS_SGM-775`` (Version 11.3 build 42)
+-  ``FVP_RD_E1Edge`` (Version 11.3 build 42)
+-  ``FVP_RD_N1Edge`` (Version 11.3 build 42)
 -  ``Foundation_Platform``
 
 The latest version of the AArch32 build of TF-A has been tested on the following