Help: Organize and clarify `cmake_minimum_required` documentation

State more explicitly that `cmake_policy(VERSION)` is implied and
explain the effects it has.

Help/command/cmake_minimum_required.rst

@@ -1,29 +1,14 @@
 cmake_minimum_required
 ----------------------
 
-Set the minimum required version of cmake for a project.
-
-::
+Set the minimum required version of cmake for a project and
+update `Policy Settings`_ to match the version given::
 
   cmake_minimum_required(VERSION major.minor[.patch[.tweak]]
                          [FATAL_ERROR])
 
 If the current version of CMake is lower than that required it will
-stop processing the project and report an error.  When a version
-higher than 2.4 is specified the command implicitly invokes
-
-::
-
-  cmake_policy(VERSION major[.minor[.patch[.tweak]]])
-
-which sets the cmake policy version level to the version specified.
-When version 2.4 or lower is given the command implicitly invokes
-
-::
-
-  cmake_policy(VERSION 2.4)
-
-which enables compatibility features for CMake 2.4 and lower.
+stop processing the project and report an error.
 
 The ``FATAL_ERROR`` option is accepted but ignored by CMake 2.6 and
 higher.  It should be specified so CMake versions 2.4 and lower fail
@@ -39,3 +24,27 @@ with an error instead of just a warning.
   Calling ``cmake_minimum_required()`` inside a :command:`function`
   limits some effects to the function scope when invoked.  Such calls
   should not be made with the intention of having global effects.
+
+Policy Settings
+^^^^^^^^^^^^^^^
+
+The ``cmake_minimum_required(VERSION)`` command implicitly invokes the
+:command:`cmake_policy(VERSION)` command to specify that the current
+project code is written for the given version of CMake.
+All policies introduced in the specified version or earlier will be
+set to use NEW behavior.  All policies introduced after the specified
+version will be unset.  This effectively requests behavior preferred
+as of a given CMake version and tells newer CMake versions to warn
+about their new policies.
+
+When a version higher than 2.4 is specified the command implicitly
+invokes::
+
+  cmake_policy(VERSION major[.minor[.patch[.tweak]]])
+
+which sets the cmake policy version level to the version specified.
+When version 2.4 or lower is given the command implicitly invokes::
+
+  cmake_policy(VERSION 2.4)
+
+which enables compatibility features for CMake 2.4 and lower.