CMake: add comment
CMake: add comment

otris/ews-cpp,bkircher/ews-cpp,m-Schlitzer/ews-cpp,otris/ews-cpp,otris/ews-cpp,otris/ews-cpp,m-Schlitzer/ews-cpp,bkircher/ews-cpp,bkircher/ews-cpp,m-Schlitzer/ews-cpp