docs(mcv): fix missing --dir parameter in NVIDIA GPU example

Added missing --dir /cache parameter to the NVIDIA GPU validation example.
The command was incomplete without specifying the output directory.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>
Signed-off-by: Maryam Tahhan <mtahhan@redhat.com>

Author: maryamtahhan

mcv/docs/no-gpu-usage.md

@@ -67,7 +67,7 @@ podman build --target mcv-nvidia -t quay.io/gkm/mcv:nvidia -f mcv/images/amd64.d
 # Use with NVIDIA GPU
 podman run --rm --device nvidia.com/gpu=all \
   -v /path/to/cache:/cache quay.io/gkm/mcv:nvidia \
-  --extract --image quay.io/myorg/cache:v1
+  --extract --image quay.io/myorg/cache:v1 --dir /cache
 ```
 
 ## Usage Examples