cli/command: fix GoDoc referencing wrong const

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

Author: thaJeztah

cli/command/cli.go

@@ -381,7 +381,7 @@ func (cli *DockerCli) ContextStore() store.Store {
 // the "default" context is used if:
 //
 //   - The "--host" option is set
-//   - The "DOCKER_HOST" ([DefaultContextName]) environment variable is set
+//   - The "DOCKER_HOST" ([client.EnvOverrideHost]) environment variable is set
 //     to a non-empty value.
 //
 // In these cases, the default context is used, which uses the host as