Help: Spell out MFC

And shorten text that was hard to understand and redundant.

Help/prop_tgt/WIN32_EXECUTABLE.rst

@@ -7,6 +7,7 @@ When this property is set to true the executable when linked on
 Windows will be created with a WinMain() entry point instead of just
 main().  This makes it a GUI executable instead of a console application.
 See the :variable:`CMAKE_MFC_FLAG` variable documentation to
-configure use of MFC for WinMain executables.  This property is
-initialized by the value of the :variable:`CMAKE_WIN32_EXECUTABLE`
-variable if it is set when a target is created.
+configure use of the Microsoft Foundation Classes (MFC) for WinMain
+executables.  This property is initialized by the value of the
+:variable:`CMAKE_WIN32_EXECUTABLE` variable if it is set when
+a target is created.

Help/variable/CMAKE_MFC_FLAG.rst

@@ -1,15 +1,16 @@
 CMAKE_MFC_FLAG
 --------------
 
-Tell cmake to use MFC for an executable or dll.
+Use the MFC library for an executable or dll.
 
-This can be set in a ``CMakeLists.txt`` file and will enable MFC in the
-application.  It should be set to ``1`` for the static MFC library, and ``2``
-for the shared MFC library.  This is used in Visual Studio
-project files.  The CMakeSetup dialog used MFC and the ``CMakeLists.txt``
-looks like this:
+Enables the use of the Microsoft Foundation Classes (MFC).
+It should be set to ``1`` for the static MFC library, and
+``2`` for the shared MFC library.  This is used in Visual Studio
+project files.
 
-::
+Usage example:
+
+.. code-block:: cmake
 
   add_definitions(-D_AFXDLL)
   set(CMAKE_MFC_FLAG 2)