fix project file version

readme.md

@@ -264,7 +264,7 @@ There are 2 files in TinyXML-2:
 And additionally a test file:
 * xmltest.cpp
 
-Simply compile and run. There is a visual studio 2010 project included, a simple Makefile, 
+Simply compile and run. There is a visual studio 2015 project included, a simple Makefile, 
 an Xcode project, a Code::Blocks project, and a cmake CMakeLists.txt included to help you. 
 The top of tinyxml.h even has a simple g++ command line if you are are *nix and don't want 
 to use a build system.