Windows build docs update: Update 2 -> Update 3

docs/windows_build_instructions.md

 # Windows Build Instructions
 
 ## Common checkout instructions
 
 This page covers Windows-specific setup and configuration. The
 [general checkout
 instructions](http://dev.chromium.org/developers/how-tos/get-the-code) cover
 installing depot tools and checking out the code via git.
 
 ## Setting up Windows
 
 You must set your Windows system locale to English, or else you may get
 build errors about "The file contains a character that cannot be
 represented in the current code page."
 
 ### Setting up the environment for Visual Studio
 
-You must build with Visual Studio 2015 Update 2; no other version is
+You must build with Visual Studio 2015 Update 3; no other version is
 supported.
 
 You must have Windows 7 x64 or later. x86 OSs are unsupported.
 
 ## Getting the compiler toolchain
 
 Follow the appropriate path below:
 
 ### Open source contributors
 
 As of March 11, 2016 Chromium requires Visual Studio 2015 to build.
 
-Install Visual Studio 2015 Update 2 or later - Community Edition
+Install Visual Studio 2015 Update 3 or later - Community Edition
 should work if its license is appropriate for you. Use the Custom Install option
 and select:
 
 - Visual C++, which will select three sub-categories including MFC
 - Universal Windows Apps Development Tools > Tools
 - Universal Windows Apps Development Tools > Windows 10 SDK (10.0.10586)
 
 You must have the 10586 SDK installed or else you will hit compile errors such
 as redefined macros.
 
@@ skipping 57 matching lines @@
 3.  Store the build tree on a fast disk (preferably SSD).
 4.  If you are primarily going to be doing debug development builds, you
     should use the component build. Set the [build
     arg](https://www.chromium.org/developers/gn-build-configuration)
     `is_component_build = true`.
     This will generate many DLLs and enable incremental linking, which makes
     linking **much** faster in Debug.
 
 Still, expect build times of 30 minutes to 2 hours when everything has to
 be recompiled.