[NFC][DF] Comment on why we need to declare namespace alias twice
[NFC][DF] Comment on why we need to declare namespace alias twice

Some linters actually warn that the alias declaration is unused,
so it's better to clarify why they are wrong.

olifre/root,olifre/root,olifre/root,olifre/root,olifre/root,olifre/root,olifre/root,olifre/root,olifre/root,olifre/root,olifre/root