fix(helm): modify `helm repo update` help info

The former help info may cause misunderstanding that this command
can update content of charts existing in remote respositories while
it does pull charts' info from remote repositories.

This trivial modification leads better understanding.

cmd/helm/repo_update.go

@@ -55,7 +55,7 @@ func newRepoUpdateCmd(out io.Writer) *cobra.Command {
 	cmd := &cobra.Command{
 		Use:     "update",
 		Aliases: []string{"up"},
-		Short:   "update information on available charts in the chart repositories",
+		Short:   "update information of available charts locally from chart repositories",
 		Long:    updateDesc,
 		RunE: func(cmd *cobra.Command, args []string) error {
 			u.home = settings.Home

docs/helm/helm_repo.md

@@ -29,6 +29,6 @@ Example usage:
 * [helm repo index](helm_repo_index.md)	 - generate an index file given a directory containing packaged charts
 * [helm repo list](helm_repo_list.md)	 - list chart repositories
 * [helm repo remove](helm_repo_remove.md)	 - remove a chart repository
-* [helm repo update](helm_repo_update.md)	 - update information on available charts in the chart repositories
+* [helm repo update](helm_repo_update.md)	 - update information of available charts locally from chart repositories
 
 ###### Auto generated by spf13/cobra on 29-May-2017

docs/helm/helm_repo_update.md

 ## helm repo update
 
-update information on available charts in the chart repositories
+update information of available charts locally from chart repositories
 
 ### Synopsis
 

docs/man/man1/helm_repo_update.1

@@ -5,7 +5,7 @@
 
 .SH NAME
 .PP
-helm\-repo\-update \- update information on available charts in the chart repositories
+helm\-repo\-update \- update information of available charts locally from chart repositories
 
 
 .SH SYNOPSIS