Help: Revise and format policy CMP0025 and CMP0047 docs

Add inline reST markup as appropriate.  Word CMP0047 docs more like
those of CMP0025.  State explicitly that the policies must be set
before the project or enable_language command calls.

Help/policy/CMP0025.rst

 CMP0025
 -------
 
-Compiler id for Apple Clang is now AppleClang.
+Compiler id for Apple Clang is now ``AppleClang``.
 
-CMake >= 3.0 recognize that Apple Clang is a different compiler
+CMake 3.0 and above recognize that Apple Clang is a different compiler
 than upstream Clang and that they have different version numbers.
-CMake now prefers to present this to projects by setting
-CMAKE_<LANG>_COMPILER_ID to "AppleClang" instead of "Clang".  However,
-existing projects may assume the compiler id for Apple Clang is just
-"Clang" as it was in CMake < 3.0.  Therefore this policy determines
-for Apple Clang which compiler id to report in
-CMAKE_<LANG>_COMPILER_ID after <LANG> is enabled by the project() or
-enable_language() command.
+CMake now prefers to present this to projects by setting the
+:variable:`CMAKE_<LANG>_COMPILER_ID` variable to ``AppleClang`` instead
+of ``Clang``.  However, existing projects may assume the compiler id for
+Apple Clang is just ``Clang`` as it was in CMake versions prior to 3.0.
+Therefore this policy determines for Apple Clang which compiler id to
+report in the :variable:`CMAKE_<LANG>_COMPILER_ID` variable after
+language ``<LANG>`` is enabled by the :command:`project` or
+:command:`enable_language` command.  The policy must be set prior
+to the invocation of either command.
 
-The OLD behavior for this policy is to use compiler id "Clang".  The
-NEW behavior for this policy is to use compiler id "AppleClang".
+The OLD behavior for this policy is to use compiler id ``Clang``.  The
+NEW behavior for this policy is to use compiler id ``AppleClang``.
 
 This policy was introduced in CMake version 3.0.  CMake version
 |release| warns when the policy is not set and uses OLD behavior.  Use
-the cmake_policy command to set it to OLD or NEW explicitly.
+the :command:`cmake_policy` command to set it to OLD or NEW explicitly.

Help/policy/CMP0047.rst

 CMP0047
 -------
 
-Use QCC compiler id for the qcc drivers on QNX.
+Use ``QCC`` compiler id for the qcc drivers on QNX.
 
-CMake 2.8.12 and lower assigned the QNX qcc and QCC compiler drivers the "GNU"
-compiler id.
+CMake 3.0 and above recognize that the QNX qcc compiler driver is
+different from the GNU compiler.
+CMake now prefers to present this to projects by setting the
+:variable:`CMAKE_<LANG>_COMPILER_ID` variable to ``QCC`` instead
+of ``GNU``.  However, existing projects may assume the compiler id for
+QNX qcc is just ``GNU`` as it was in CMake versions prior to 3.0.
+Therefore this policy determines for QNX qcc which compiler id to
+report in the :variable:`CMAKE_<LANG>_COMPILER_ID` variable after
+language ``<LANG>`` is enabled by the :command:`project` or
+:command:`enable_language` command.  The policy must be set prior
+to the invocation of either command.
 
-The OLD behavior for this policy is to use the "GNU" compiler id for the qcc
-and QCC compiler drivers. The NEW behavior for this policy is to use the "QCC"
-compiler id for those drivers.
+The OLD behavior for this policy is to use the ``GNU`` compiler id
+for the qcc and QCC compiler drivers. The NEW behavior for this policy
+is to use the ``QCC`` compiler id for those drivers.
 
 This policy was introduced in CMake version 3.0.
 CMake version |release| warns when the policy is not set and uses
-OLD behavior.  Use the cmake_policy command to set it to OLD or
-NEW explicitly.
+OLD behavior.  Use the :command:`cmake_policy` command to set it to
+OLD or NEW explicitly.