Merge pull request #544 from openset/develop

 Update: CmdUpdate

Author: Shuo

Diff for: helper/README.md

@@ -21,7 +21,7 @@ The commands are:
 	open        	open a problem solution in browser
 	test        	run go test
 	description 	build all problems description file
-	update      	update self
+	update      	update or upgrade self
 	clean       	remove cached files
 	version     	print leetcode version
 	help        	show command usage

Diff for: internal/update/update.go

@@ -1,6 +1,7 @@
 package update
 
 import (
+	"fmt"
 	"os"
 	"os/exec"
 
@@ -10,8 +11,8 @@ import (
 var CmdUpdate = &base.Command{
 	Run:       runUpdate,
 	UsageLine: "update",
-	Short:     "update self",
-	Long:      "automates testing the packages.",
+	Short:     "update or upgrade self",
+	Long:      fmt.Sprintf("fetch the newest version of %s.", base.CmdName),
 }
 
 func runUpdate(cmd *base.Command, args []string) {