Fix misleading use-alias help doc (#2692)

Signed-off-by: albertteoh <albert.teoh@logz.io>

plugin/storage/es/options.go

@@ -239,7 +239,7 @@ func addFlags(flagSet *flag.FlagSet, nsConfig *namespaceConfig) {
 		nsConfig.UseReadWriteAliases,
 		"Use read and write aliases for indices. Use this option with Elasticsearch rollover "+
 			"API. It requires an external component to create aliases before startup and then performing its management. "+
-			"Note that "+nsConfig.namespace+suffixMaxSpanAge+" is not taken into the account and has to be substituted by external component managing read alias.")
+			"Note that "+nsConfig.namespace+suffixMaxSpanAge+" will influence trace search window start times.")
 	flagSet.Bool(
 		nsConfig.namespace+suffixCreateIndexTemplate,
 		nsConfig.CreateIndexTemplates,