Merge pull request #1665 from jcrben/patch-1

Note caveat with detaching using key sequence

docs/reference/commandline/attach.md

@@ -44,8 +44,8 @@ from different sessions on the Docker host.
 
 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
-the container. You can detach from a container and leave it running using the
- `CTRL-p CTRL-q` key sequence.
+the container. If the container was run with `-i` and `-t`, you can detach from
+a container and leave it running using the `CTRL-p CTRL-q` key sequence.
 
 > **Note:**
 > A process running as PID 1 inside a container is treated specially by