[GN docs] Add missing word in gn actions help string

tools/gn/functions_target.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 "tools/gn/functions.h"
 
 #include "tools/gn/config_values_generator.h"
 #include "tools/gn/err.h"
 #include "tools/gn/parse_tree.h"
 #include "tools/gn/scope.h"
@@ skipping 73 matching lines @@
     "  action are started. This can give additional parallelism in the build\n"\
     "  for runtime-only dependencies.\n"
 
 const char kAction[] = "action";
 const char kAction_HelpShort[] =
     "action: Declare a target that runs a script a single time.";
 const char kAction_Help[] =
     "action: Declare a target that runs a script a single time.\n"
     "\n"
     "  This target type allows you to run a script a single time to produce\n"
-    "  or more output files. If you want to run a script once for each of a\n"
-    "  set of input files, see \"gn help action_foreach\".\n"
+    "  one or more output files. If you want to run a script once for each of\n"
+    "  a set of input files, see \"gn help action_foreach\".\n"
     "\n"
     "Inputs\n"
     "\n"
     "  In an action the \"sources\" and \"inputs\" are treated the same:\n"
     "  they're both input dependencies on script execution with no special\n"
     "  handling. If you want to pass the sources to your script, you must do\n"
     "  so explicitly by including them in the \"args\". Note also that this\n"
     "  means there is no special handling of paths since GN doesn't know\n"
     "  which of the args are paths and not. You will want to use\n"
     "  rebase_path() to convert paths to be relative to the root_build_dir.\n"
@@ skipping 668 matching lines @@
   const Template* templ = scope->GetTemplate(target_type);
   if (templ)
     return templ->Invoke(scope, function, sub_args, block, err);
 
   // Otherwise, assume the target is a built-in target type.
   return ExecuteGenericTarget(target_type.c_str(), scope, function, sub_args,
                               block, err);
 }
 
 }  // namespace functions