Mention command to check compute capability

That is, CUDA compute capability. This enables checking locally.

README.md

@@ -283,6 +283,12 @@ compute capabilities of the target GPU architectures that kernels will
 be built for. Entries can be separated using semicola. Compute
 capabilities for various CUDA-enabled GPUs can be found on this page:
 https://developer.nvidia.com/cuda-gpus  
+You can also manually check your CUDA-enabled GPU's compute capability
+using:
+
+```shell
+nvidia-smi --query-gpu=compute_cap --format=csv,noheader
+```
 
 For example, if we want to build kernels that target NVIDIA V100
 (compute capability 7.0), NVIDIA A100 (compute capability 8.0), and