feat(rh850): add build badge to README.md

Signed-off-by: David Cerdeira <davidmcerdeira@gmail.com>

Author: DavidMCerdeira

README.md

@@ -3,6 +3,7 @@
 ![code quality workflow](https://github.com/bao-project/bao-hypervisor/actions/workflows/code-quality.yaml/badge.svg)
 ![arm build workflow](https://github.com/bao-project/bao-hypervisor/actions/workflows/build-arm.yaml/badge.svg)
 ![riscv build workflow](https://github.com/bao-project/bao-hypervisor/actions/workflows/build-riscv.yaml/badge.svg)
+![rh850 build workflow](https://github.com/bao-project/bao-hypervisor/actions/workflows/build-v850.yaml/badge.svg)
 
 Introduction
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