General comment cleaning / refactoring for Mac Installer

chrome/installer/mac/app/SystemInfo.m

 // Copyright 2016 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 <mach-o/arch.h>
 
 #import "SystemInfo.h"
 
 @implementation SystemInfo
 
 + (NSString*)getArch {
+  // NOTE: It seems the below function `NSGetLocalArchInfo` returns an
+  // arch->name that is either "x84_64h" or "i486".
   const NXArchInfo* arch = NXGetLocalArchInfo();
   NSString* archName = [NSString stringWithUTF8String:arch->name];
   return archName;
 }
 
 + (NSString*)getOSVersion {
   NSDictionary* systemVersion =
       [NSDictionary dictionaryWithContentsOfFile:
                         @"/System/Library/CoreServices/SystemVersion.plist"];
   NSString* versionNumber = [systemVersion objectForKey:@"ProductVersion"];
 
   return versionNumber;
 }
 
 @end