Updated description of location for downloading MS Windows Build Tools.

README.rst

@@ -110,9 +110,9 @@ Mac OS X
 Microsoft Windows
 ^^^^^^^^^^^^^^^^^
 
-* Download and install Microsoft Visual C++ Build Tools 2015 directly from http://go.microsoft.com/fwlink/?LinkId=691126. Use the default installation options.
+* Download and install Microsoft Visual C++ Build Tools 2015 Update 3 directly from http://go.microsoft.com/fwlink/?LinkId=691126. Use the default installation options.
 
-You can also download Microsoft Visual C++ Build Tools 2015 by going to https://www.visualstudio.com/en-us/downloads/download-visual-studio-vs.aspx and choosing Tools for Visual Studio 2015 -> Microsoft Visual C++ Build Tools 2015.
+You can also download Microsoft Visual C++ Build Tools 2015 by going to https://www.visualstudio.com/downloads/, and the section Other Tools and Frameworks -> Microsoft Visual C++ Build Tools 2015 Update 3.
 
 3. Build and install gprMax
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