clarify URL help

main.go

@@ -152,7 +152,7 @@ Options can also be specified as environment variables $CHART_SVR_<name>
 	}
 	pflag.StringVar(&dir, "dir", getEnvDefault("CHART_SVR_DIR", "."), "Chart report dir")
 	pflag.StringVar(&host, "host", getEnvDefault("CHART_SVR_HOST", ":8080"), "Host to bind to [<host>]:<port>")
-	pflag.StringVar(&url, "url", getEnvDefault("CHART_SVR_URL", ""), "URL to the chart repository")
+	pflag.StringVar(&url, "url", getEnvDefault("CHART_SVR_URL", ""), "Externally accessible URL to the chart repository")
 	pflag.Parse()
 
 	if len(url) == 0 {