Clarify meaning of docker attach

Signed-off-by: Misty Stanley-Jones <misty@docker.com>

cli/command/container/attach.go

@@ -28,7 +28,7 @@ func NewAttachCommand(dockerCli *command.DockerCli) *cobra.Command {
 
 	cmd := &cobra.Command{
 		Use:   "attach [OPTIONS] CONTAINER",
-		Short: "Attach to a running container",
+		Short: "Attach local standard input, output, and error streams to a running container",
 		Args:  cli.ExactArgs(1),
 		RunE: func(cmd *cobra.Command, args []string) error {
 			opts.container = args[0]

docs/reference/commandline/attach.md

@@ -18,7 +18,7 @@ keywords: "attach, running, container"
 ```markdown
 Usage: docker attach [OPTIONS] CONTAINER
 
-Attach to a running container
+Attach local standard input, output, and error streams to a running container
 
 Options:
       --detach-keys string   Override the key sequence for detaching a container
@@ -29,10 +29,13 @@ Options:
 
 ## Description
 
-Use `docker attach` to attach to a running container using the container's ID
-or name, either to view its ongoing output or to control it interactively.
+Use `docker attach` to attach your terminal's standard input, output, and error
+(or any combination of the three) to a running container using the container's
+ID or name. This allows you to view its ongoing output or to control it
+interactively, as though the commands were running directly in your terminal.
+
 You can attach to the same contained process multiple times simultaneously,
-screen sharing style, or quickly view the progress of your detached process.
+even as a different user with the appropriate permissions.
 
 To stop a container, use `CTRL-c`. This key sequence sends `SIGKILL` to the
 container. If `--sig-proxy` is true (the default),`CTRL-c` sends a `SIGINT` to