ENH: add documentation support for modules

Modules/CMake.cmake

Modules/CMakeBackwardCompatibilityC.cmake

Modules/CMakeBackwardCompatibilityCXX.cmake

Modules/CMakeCInformation.cmake

Modules/CMakeCXXInformation.cmake

Modules/CMakeCommonLanguageInclude.cmake

Modules/CMakeDetermineCCompiler.cmake

Modules/CMakeDetermineCXXCompiler.cmake

Modules/CMakeDetermineFortranCompiler.cmake

Modules/CMakeDetermineJavaCompiler.cmake

Modules/CMakeDetermineRCCompiler.cmake

Modules/CMakeDetermineSystem.cmake

Modules/CMakeExportBuildSettings.cmake

Modules/CMakeFindFrameworks.cmake

Modules/CMakeFortranInformation.cmake

Modules/CMakeImportBuildSettings.cmake

Modules/CMakeJavaInformation.cmake

Modules/CMakePrintSystemInformation.cmake

Modules/CMakeRCInformation.cmake

Modules/CMakeSystemSpecificInformation.cmake