Update README to reflecto possible error when compiling python gdal lib on osx
Update README to reflecto possible error when compiling python gdal lib on osx

jmwenda/nationmaps,datapolitan/cartodb20,jmwenda/nationmaps,jmwenda/nationmaps,datapolitan/cartodb20,datapolitan/cartodb20,datapolitan/cartodb20,jmwenda/nationmaps