Mark non-unique / "ill-defined" spaces

[felixpernegger]

Some spaces we have in pibase are not uniquely defined but depend on the choice of some things. See i.e. https://topology.pi-base.org/spaces/S145
(basically all spaces dependent on some choice)

I think its fine to have those, but we should write a warning in the description, as in S145.

Those non-unique spaces include (but probably not limited to):

S145, (most likely) S216, (most likely) S147, (most likely) S148

[Moniker1998]

@felixpernegger I find that fine, but one would have to be careful.
It's not sufficient to say "this is not unique because it requires arbitrary choices" as the choices might result in homeomorphic spaces. So such disclaimer would need a proof