Add DRA Performance Testing & Scalability Documentation (#107)

* Initial plan

* Add DRA performance testing documentation

Co-authored-by: pacoxu <[email protected]>

---------

Co-authored-by: copilot-swe-agent[bot] <[email protected]>
Co-authored-by: pacoxu <[email protected]>

Author: Copilot

README.md

@@ -85,6 +85,7 @@ management. Detailed guides:
 [Scheduling Optimization](./docs/kubernetes/scheduling-optimization.md) |
 [Isolation](./docs/kubernetes/isolation.md) |
 [DRA](./docs/kubernetes/dra.md) |
+[DRA Performance Testing](./docs/kubernetes/dra-performance-testing.md) |
 [NVIDIA GPU Operator](./docs/kubernetes/nvidia-gpu-operator.md) |
 [NRI](./docs/kubernetes/nri.md)