Move manpage gen to separate binary

This moves the man page generation to a separate binary

Signed-off-by: Michael Crosby <crosbymichael@gmail.com>

cmd/ctr/main.go

@@ -21,7 +21,6 @@ import (
 	"os"
 
 	"github.com/containerd/containerd/cmd/ctr/app"
-	"github.com/containerd/containerd/pkg/climan"
 	"github.com/containerd/containerd/pkg/seed"
 	"github.com/urfave/cli"
 )
@@ -35,7 +34,6 @@ func init() {
 func main() {
 	app := app.New()
 	app.Commands = append(app.Commands, pluginCmds...)
-	app.Commands = append(app.Commands, climan.Command)
 	if err := app.Run(os.Args); err != nil {
 		fmt.Fprintf(os.Stderr, "ctr: %s\n", err)
 		os.Exit(1)