CDRIVER-4376 note that Visual Studio 2013 is required (#998)

Author: kevinAlbs

src/libmongoc/doc/installing.rst

@@ -132,7 +132,7 @@ The ``cmake`` utility is also required. First `install Homebrew according to its
 Build environment on Windows with Visual Studio
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-Building on Windows requires Windows Vista or newer and Visual Studio 2010 or newer. Additionally, ``cmake`` is required to generate Visual Studio project files.  Installation of these components on Windows is beyond the scope of this document.
+Building on Windows requires Windows Vista or newer and Visual Studio 2013 or newer. Additionally, ``cmake`` is required to generate Visual Studio project files.  Installation of these components on Windows is beyond the scope of this document.
 
 Build environment on Windows with MinGW-W64 and MSYS2
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