mise.toml in the directory of MISE_CEILING_PATHS is ignored

[hehaoqian]

The documentation does not say
mise.toml at the directory of MISE_CEILING_PATHS is ignored.

For example, if MISE_CEILING_PATHS is "/foo",
then /foo/mise.toml is ignored, but /foo/bar/mise.toml is recognized.

I thought that MISE_CEILING_PATHS includes the mise.toml in its dir

I read debug log and unittests of all_dir() in https://github.com/jdx/mise/blob/main/src/file.rs,
and then understand the meaning of MISE_CEILING_PATHS
that mise.toml inside MISE_CEILING_PATHS is ignored.

The current doc for MISE_CEILING_PATHS is a bit confusing,
OR the current behavior is not the expected bahavior.

It seems weird to set MISE_CEILING_PATHS to the graphparent of mise.toml, instead of parent of mise.toml, in order to use mise.toml.

But changing this will affect the compability. I suggest to update the documentation.