Update Windows readme for CMake

README.windows

-This project has begun being ported to Windows.  A working solution
-file exists in this directory:
-    google-glog.sln
+This project has been ported to Windows, including stack tracing, signal
+handling, and unit tests.
 
-You can load this solution file into VC++ 9.0 (Visual Studio
-2008).  You may also be able to use this solution file with older
-Visual Studios by converting the solution file.
+A Visual Studio solution file is explicitly not provided because it is not
+maintainable. Instead, a CMake build system exists to generate the correct
+solution for your version of Visual Studio.
 
-Note that stack tracing and some unittests are not ported
-yet.
+In short,
+  (1) Install CMake from: https://cmake.org/download/
+  (2) With CMake on your PATH, run `cmake .` to generate the build files
+  (3) Either use `cmake --build`, or open the generated solution
 
-You can also link glog code in statically -- see the example project
-libglog_static and logging_unittest_static, which does this.  For this
-to work, you'll need to add "/D GOOGLE_GLOG_DLL_DECL=" to the compile
-line of every glog's .cc file.
-
-I have little experience with Windows programming, so there may be
-better ways to set this up than I've done!  If you run across any
-problems, please post to the google-glog Google Group, or report
-them on the google-glog Google Code site:
-   http://groups.google.com/group/google-glog
-   https://github.com/google/glog/issues
-
--- Shinichiro Hamaji
-
-Last modified: 23 January 2009
+CMake provides different generators, and by default will pick the most relevant
+one to your environment. If you need a specific version of Visual Studio, use
+`cmake . -G <generator-name>`, and see `cmake --help` for the available
+generators. Also see `-T <toolset-name>`, which can used to request the native
+x64 toolchain with `-T host=x64`.
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