Stop pointing to "gn help toolchain" in that very help message.

tools/gn/function_toolchain.cc

 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <algorithm>
 #include <limits>
 #include <utility>
 
 #include "tools/gn/err.h"
 #include "tools/gn/functions.h"
@@ skipping 303 matching lines @@
     "    The tool() function call specifies the commands commands to run for\n"
     "    a given step. See \"gn help tool\".\n"
     "\n"
     "  toolchain_args\n"
     "    Overrides for build arguments to pass to the toolchain when invoking\n"
     "    it. This is a variable of type \"scope\" where the variable names\n"
     "    correspond to varibles in declare_args() blocks.\n"
     "\n"
     "    When you specify a target using an alternate toolchain, the master\n"
     "    build configuration file is re-interpreted in the context of that\n"
-    "    toolchain (see \"gn help toolchain\"). The toolchain_args allows you\n"
-    "    to control the arguments passed into this alternate invocation of\n"
-    "    the build.\n"
+    "    toolchain. toolchain_args allows you to control the arguments\n"
+    "    passed into this alternate invocation of the build.\n"
     "\n"
     "    Any default system arguments or arguments passed in via \"gn args\"\n"
     "    will also be passed to the alternate invocation unless explicitly\n"
     "    overridden by toolchain_args.\n"
     "\n"
     "    The toolchain_args will be ignored when the toolchain being defined\n"
     "    is the default. In this case, it's expected you want the default\n"
     "    argument values.\n"
     "\n"
     "    See also \"gn help buildargs\" for an overview of these arguments.\n"
@@ skipping 742 matching lines @@
   if (err->has_error())
     return Value();
 
   block_scope->DetachFromContaining();
   scope->SetValue("toolchain_args", Value(function, std::move(block_scope)),
                   function);
   return Value();
 }
 
 }  // namespace functions