Align with other cli descriptions

Signed-off-by: yupeng <yu.peng36@zte.com.cn>

cli/command/registry/login.go

@@ -23,7 +23,7 @@ func NewLoginCommand(dockerCli *command.DockerCli) *cobra.Command {
 
 	cmd := &cobra.Command{
 		Use:   "login [OPTIONS] [SERVER]",
-		Short: "Log in to a Docker registry.",
+		Short: "Log in to a Docker registry",
 		Long:  "Log in to a Docker registry.\nIf no server is specified, the default is defined by the daemon.",
 		Args:  cli.RequiresMaxArgs(1),
 		RunE: func(cmd *cobra.Command, args []string) error {

cli/command/registry/logout.go

@@ -15,7 +15,7 @@ import (
 func NewLogoutCommand(dockerCli *command.DockerCli) *cobra.Command {
 	cmd := &cobra.Command{
 		Use:   "logout [SERVER]",
-		Short: "Log out from a Docker registry.",
+		Short: "Log out from a Docker registry",
 		Long:  "Log out from a Docker registry.\nIf no server is specified, the default is defined by the daemon.",
 		Args:  cli.RequiresMaxArgs(1),
 		RunE: func(cmd *cobra.Command, args []string) error {

cmd/docker/docker.go

@@ -23,7 +23,7 @@ func newDockerCommand(dockerCli *command.DockerCli) *cobra.Command {
 
 	cmd := &cobra.Command{
 		Use:              "docker [OPTIONS] COMMAND [arg...]",
-		Short:            "A self-sufficient runtime for containers.",
+		Short:            "A self-sufficient runtime for containers",
 		SilenceUsage:     true,
 		SilenceErrors:    true,
 		TraverseChildren: true,