Update README.md with Armv9-A support. (#386)

We support v9-A code-generation. We map the v9-A family to the v8-A
C-libraries.

Author: smithp35

arm-software/embedded/README.md

@@ -34,6 +34,7 @@ embedded and realtime operating systems.
 - AArch32 Armv8-R
 - AArch64 Armv8-A
 - AArch64 Armv8-R
+- AArch64 Armv9-A
 
 ## C++ support