Imprecise documentation on automatic _GLIBCXX_USE_CXX11_ABI?

The [documentation](https://docs.conan.io/en/latest/howtos/manage_gcc_abi.html) says `If you are using the CMake build helper or the AutotoolsBuildEnvironment build helper Conan will automatically adjust the _GLIBCXX_USE_CXX11_ABI flag to manage the ABI.`

However, I can only get that working using `cmake` generator and calling `conan_basic_setup` in my `CMakeLists.txt`.