Add update command

commands/commands.go

@@ -90,6 +90,7 @@ func All() []*Command {
 	all = append(all, cmdAlias)
 	all = append(all, cmdVersion)
 	all = append(all, cmdHelp)
+	all = append(all, cmdUpdate)
 
 	return all
 }

commands/help.go

@@ -86,6 +86,7 @@ GitHub Commands:
    issue          Manipulate issues (beta)
 
 See 'git help <command>' for more information on a specific command.
+Run 'git update' to update to the latest version of gh.
 `
 
 func printUsage() {

commands/update.go

@@ -0,0 +1,20 @@
+package commands
+
+import (
+	"os"
+)
+
+var cmdUpdate = &Command{
+	Run:   update,
+	Usage: "update",
+	Short: "Update gh",
+	Long: `Update gh with the latest version.
+
+Examples:
+  git update
+`,
+}
+
+func update(cmd *Command, args *Args) {
+	os.Exit(0)
+}