Re-apply "docs: document ssh multiplexing env"

This reverts commit 29734b9.

Signed-off-by: Nicolas De Loof <nicolas.deloof@gmail.com>

Author: ndeloof

docs/reference/commandline/docker.md

@@ -126,11 +126,12 @@ The following environment variables control the behavior of the `docker` command
 | `DOCKER_DEFAULT_PLATFORM`     | Default platform for commands that take the `--platform` flag.                                                                                                                                                                                                    |
 | `DOCKER_HIDE_LEGACY_COMMANDS` | When set, Docker hides "legacy" top-level commands (such as `docker rm`, and `docker pull`) in `docker help` output, and only `Management commands` per object-type (e.g., `docker container`) are printed. This may become the default in a future release.      |
 | `DOCKER_HOST`                 | Daemon socket to connect to.                                                                                                                                                                                                                                      |
+| `DOCKER_SSH_NO_MUX`           | If set will turn off SSH multiplexing when connecting to daemon through SSH.                                                                                                                                                                                      |
+| `DOCKER_SSH_MUX_PERSIST`      | Set a duration for keeping SSH multiplexing socket alive between commands (e.g `60s`).                                                                                                                                                                            |
 | `DOCKER_TLS`                  | Enable TLS for connections made by the `docker` CLI (equivalent of the `--tls` command-line option). Set to a non-empty value to enable TLS. Note that TLS is enabled automatically if any of the other TLS options are set.                                      |
 | `DOCKER_TLS_VERIFY`           | When set Docker uses TLS and verifies the remote. This variable is used both by the `docker` CLI and the [`dockerd` daemon](https://docs.docker.com/reference/cli/dockerd/)                                                                                       |
 | `BUILDKIT_PROGRESS`           | Set type of progress output (`auto`, `plain`, `tty`, `rawjson`) when [building](https://docs.docker.com/reference/cli/docker/image/build/) with [BuildKit backend](https://docs.docker.com/build/buildkit/). Use plain to show container output (default `auto`). |
-| `NO_COLOR`                    | Disable any ANSI escape codes in the output in accordance with https://no-color.org/
-                                                                                                             |
+| `NO_COLOR`                    | Disable any ANSI escape codes in the output in accordance with https://no-color.org/                                                                                                                                                                              |
 
 Because Docker is developed using Go, you can also use any environment
 variables used by the Go runtime. In particular, you may find these useful: