Fix docker exec command help messages
@@ -657,7 +657,7 @@ You'll need two shells for this example.
Usage: docker exec [OPTIONS] CONTAINER COMMAND [ARG...]
- Run a command in an existing container
+ Run a command in a running container
-d, --detach=false Detached mode: run command in the background
-i, --interactive=false Keep STDIN open even if not attached
