remove incorrect syntax usage info

Author: lsqproduction

packages/core/lib/commands/help/meta.js

@@ -1,16 +1,9 @@
-const OS = require("os");
-
 module.exports = {
   command: "help",
   description:
     "List all commands or provide information about a specific command",
   help: {
-    usage:
-      "truffle help [<command> [<subCommand>]]" +
-      OS.EOL +
-      "                truffle --help [<command> [<subCommand>]]" +
-      OS.EOL +
-      "                truffle [<command> [<subCommand>]] --help",
+    usage: "truffle help [<command> [<subCommand>]]",
     options: [
       {
         option: "<command>",