update README

Author: crazy-max

README.md

@@ -94,16 +94,16 @@ docker buildx bake image-all
 Following platforms for this image are available:
 
 ```
-$ docker run --rm mplatform/mquery crazymax/rtorrent-rutorrent:latest
-Image: crazymax/rtorrent-rutorrent:latest
- * Manifest List: Yes
- * Supported platforms:
-   - linux/amd64
-   - linux/arm/v6
-   - linux/arm/v7
-   - linux/arm64
+$ docker buildx imagetools inspect crazymax/rtorrent-rutorrent --format "{{json .Manifest}}" | \
+  jq -r '.manifests[] | select(.platform.os != null and .platform.os != "unknown") | .platform | "\(.os)/\(.architecture)\(if .variant then "/" + .variant else "" end)"'
+
+linux/amd64
+linux/arm/v6
+linux/arm/v7
+linux/arm64
 ```
 
+
 ## Environment variables
 
 ### General