README: minor addition
README: minor addition

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