docs: update ls command output sample

Signed-off-by: CrazyMax <crazy-max@users.noreply.github.com>

docs/reference/buildx_ls.md

@@ -21,7 +21,7 @@ elated_tesla *  docker-container
   elated_tesla0 unix:///var/run/docker.sock running v0.10.3  linux/amd64
   elated_tesla1 ssh://ubuntu@1.2.3.4        running v0.10.3  linux/arm64*, linux/arm/v7, linux/arm/v6
 default         docker
-  default       default                     running 20.10.14 linux/amd64
+  default       default                     running v0.8.2   linux/amd64
 ```
 
 Each builder has one or more nodes associated with it. The current builder's